Force sensor

ABSTRACT

A strain body of a force sensor according to the present invention includes a tilting structure disposed between a force receiving body and a support body, a force-receiving-body-side deformable body connecting the force receiving body and the tilting structure, and a support-body-side deformable body connecting the tilting structure and the support body. The tilting structure includes a first tilting body that extends in a second direction orthogonal to a first direction and that is elastically deformable by the action of force in the first direction.

RELATED APPLICATION

This application is a divisional of application Ser. No. 16/944,964filed on Jul. 31, 2020, which claims priority from JP 2020-029797 filedon Feb. 25, 2020, the entire contents of which are incorporated hereinby reference.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromJapanese Patent Application No. 2020-029797, filed on Feb. 25, 2020; theentire contents of which are incorporated herein by reference.

FIELD

The present invention relates to a force sensor.

BACKGROUND

Heretofore, there has been known a force sensor that outputs, as anelectric signal, force acting in a predetermined axial direction andmoment (or torque) acting around a predetermined rotation axis (e.g.,see Japanese Patent No. 6257017). This force sensor is widely used forforce control and others of various robots including industrial robots,collaborative robots, life support robots, medical robots, servicerobots, etc. Thus, improvement in performance is requested as well assafety.

For example, in a general force sensor, when force or moment is input,strain is produced by elastic deformation of a strain body constitutingthe force sensor, and displacement is caused. The magnitude of the inputforce or moment is obtained by detecting the magnitude of thedisplacement as an electric signal. Various types such as a capacitancetype and a strain gauge type exist as detection types.

While the strain body is elastically deformed, stress is applied to thestrain body. When elastic deformation of the strain body due to theapplied stress is small, displacement is small. In this case, detectionsensitivity of force or moment can deteriorate. If detection sensitivitydeteriorates, detection accuracy can deteriorate.

SUMMARY

The present invention has been made in view of such circumstances, andis indented to provide a force sensor that can improve detectionaccuracy.

The present invention provides

a force sensor comprising:

a force receiving body that receives action of force or moment to betargeted for detection;

a support body that is disposed on one side of the force receiving bodyin a first direction and that supports the force receiving body;

a strain body that connects the force receiving body and the supportbody and that is elastically deformed by the action of force or momentreceived by the force receiving body;

a detection element that detects displacement caused by elasticdeformation produced in the strain body; and

a detection circuit that outputs an electric signal indicating force ormoment acting on the strain body, on the basis of a detection result bythe detection element, wherein

the strain body includes a tilting structure disposed between the forcereceiving body and the support body, a force-receiving-body-sidedeformable body that connects the force receiving body and the tiltingstructure, the force-receiving-body-side deformable body beingelastically deformable by the action of force or moment received by theforce receiving body, and a support-body-side deformable body thatconnects the tilting structure and the support body, thesupport-body-side deformable body being elastically deformable by theaction of force or moment received by the force receiving body, and

the tilting structure includes a first tilting body that is disposed ina plane including the first direction and a second direction orthogonalto the first direction, the first tilting body extending in a directiondifferent from the first direction and being elastically deformable bythe action of force in the first direction.

In the force sensor described above,

the force-receiving-body-side deformable body may extend in the firstdirection.

In the force sensor described above,

the support-body-side deformable body may extend in the first direction.

In the force sensor described above,

the first tilting body may extend in the second direction.

In the force sensor described above,

the first tilting body may include a first force-receiving-body-sidefacing surface to which the force-receiving-body-side deformable body isconnected, the first force-receiving-body-side facing surface facing theforce receiving body, and a second force-receiving-body-side facingsurface that is disposed on both sides of the firstforce-receiving-body-side facing surface in the second direction, thesecond force-receiving-body-side facing surface facing the forcereceiving body, and the first force-receiving-body-side facing surfacemay be located on the side of the support body with respect to thesecond force-receiving-body-side facing surface.

In the force sensor described above,

a center of the first tilting body in the second direction may belocated on the side of the support body with respect to both ends in thesecond direction.

In the force sensor described above,

a center of the first tilting body in the second direction may belocated on the side of the force receiving body with respect to bothends in the second direction.

In the force sensor described above,

the tilting structure may further include a second tilting body that isdisposed between the first tilting body and the support body, the secondtilting body being disposed in a plane including the first direction andthe second direction, extending in a direction different from the firstdirection, and being elastically deformable by the action of force inthe first direction, and a pair of connecting bodies connecting one ofthe both ends of the first tilting body in the second direction and acorresponding one of the both ends of the second tilting body in thesecond direction,

the force-receiving-body-side deformable body may be connected to thefirst tilting body, and

the support-body-side deformable body may be connected to the secondtilting body.

In the force sensor described above,

the force-receiving-body-side deformable body may be located betweenboth the ends of the first tilting body in the second direction.

In the force sensor described above,

the support-body-side deformable body may be located between both theends of the second tilting body in the second direction.

In the force sensor described above,

the force-receiving-body-side deformable body and the support-body-sidedeformable body may be located at positions overlapping each other whenviewed in the first direction.

In the force sensor described above,

the tilting structure may be formed symmetrically with respect to theforce-receiving-body-side deformable body and the support-body-sidedeformable body in the second direction.

In the force sensor described above,

the spring constant of the second tilting body relative to force actingin the first direction may be different from the spring constant of thefirst tilting body relative to force acting in the first direction.

In the force sensor described above,

the second tilting body may extend in the second direction.

In the force sensor described above,

the second tilting body may include a first support-body-side facingsurface to which the support-body-side deformable body is connected, thefirst support-body-side facing surface facing the support body, and asecond support-body-side facing surface that is disposed on both sidesof the first support-body-side facing surface in the second direction,the second support-body-side facing surface facing the support body, and

the first support-body-side facing surface may be located on the side ofthe force receiving body with respect to the second support-body-sidefacing surface.

In the force sensor described above,

a center of the second tilting body in the second direction may belocated on the side of the force receiving body with respect to bothends in the second direction.

In the force sensor described above,

a center of the second tilting body in the second direction may belocated on the side of the support body with respect to both ends in thesecond direction.

In the force sensor described above,

the force receiving body and the first tilting body may be connected bythe two force-receiving-body-side deformable bodies, and

the support-body-side deformable body connects the first tilting bodyand the support body.

In the force sensor described above,

the two force-receiving-body-side deformable bodies may be located atboth the ends of the first tilting body in the second direction.

In the force sensor described above,

the support-body-side deformable body may be located between the twoforce-receiving-body-side deformable bodies in the second direction.

In the force sensor described above,

the strain body may be formed symmetrically with respect to thesupport-body-side deformable body in the second direction.

In the force sensor described above,

the first tilting body may extend in the second direction.

In the force sensor described above,

the first tilting body may include a first support-body-side facingsurface to which the support-body-side deformable body is connected, thefirst support-body-side facing surface facing the support body, and asecond support-body-side facing surface that is disposed on both sidesof the first support-body-side facing surface in the second direction,the second support-body-side facing surface facing the support body, and

the first support-body-side facing surface may be located on the side ofthe force receiving body with respect to the second support-body-sidefacing surface.

In the force sensor described above,

a center of the first tilting body in the second direction may belocated on the side of the force receiving body with respect to bothends in the second direction.

In the force sensor described above,

the force-receiving-body-side deformable body may be connected to theforce receiving body via a force-receiving-body-side seat, and

the support-body-side deformable body may be connected to the supportbody via a support-body-side seat.

In the force sensor described above,

the detection element may include a fixed electrode substrate providedon the force receiving body or the support body and a displacementelectrode substrate provided on the tilting structure, the displacementelectrode substrate facing the fixed electrode substrate, and

the displacement electrode substrate may be disposed at both ends of thetilting structure in the second direction.

In the force sensor described above,

the displacement electrode substrate may be provided on the tiltingstructure via a columnar member.

In the force sensor described above,

the displacement electrode substrate may be provided on the columnarmember via a reinforcing substrate.

In the force sensor described above,

the detection element may include a strain gauge provided on the strainbody.

In the force sensor described above,

the force receiving body and the support body may be connected by thefour strain bodies,

the four strain bodies may include a first strain body, a second strainbody, a third strain body, and a fourth strain body,

the first direction may be a Z-axis direction in an XYZthree-dimensional coordinate system,

the first strain body may be disposed on a negative side in the Y-axisdirection relative to a center of the force receiving body, the secondstrain body may be disposed on a positive side in the X-axis directionrelative to the center of the force receiving body, the third strainbody may be disposed on a positive side in the Y-axis direction relativeto the center of the force receiving body, and the fourth strain bodymay be disposed on a negative side in the X-axis direction relative tothe center of the force receiving body,

the second direction of the first strain body and the third strain bodymay be the X-axis direction, and

the second direction of the second strain body and the fourth strainbody may be the Y-axis direction.

In the force sensor described above,

at least one of the planar shape of the force receiving body and theplanar shape of the support body may be circular.

In the force sensor described above,

at least one of the planar shape of the force receiving body and theplanar shape of the support body may be rectangular.

In the force sensor described above,

the tilting structure of the strain body may be linearly formed alongthe second direction when viewed in the first direction.

In the force sensor described above,

the tilting structure of the strain body may be formed into a curvedshape when viewed in the first direction.

In the force sensor described above,

an exterior body that covers the strain body from the outside whenviewed in the first direction may further be provided.

In the force sensor described above,

the exterior body may be fixed to the support body, and is apart fromthe force receiving body.

In the force sensor described above,

a cushioning material may be interposed between the exterior body andthe force receiving body.

According to the present invention, detection accuracy can be improved.

BRIEF DESCRIPTION OF DRAWING

FIG. 1 is a perspective view illustrating one example of a robot towhich a force sensor in a first embodiment is applied.

FIG. 2 is a sectional view illustrating the force sensor in the firstembodiment, and is a view corresponding to a section along the line A-Ain FIG. 3 described later.

FIG. 3 is a plan view illustrating the force sensor in FIG. 2 .

FIG. 4 is a front view illustrating a strain body in FIG. 2 .

FIG. 5 is a view in which the strain body of the force sensorillustrated in FIG. 3 is developed in a plane.

FIG. 6 is a front view schematically illustrating a deformation state ofthe strain body in FIG. 4 when receiving force on a positive side in anX-axis direction.

FIG. 7A is a front view schematically illustrating a deformation stateof the strain body in FIG. 4 when receiving force on the positive sidein a Z-axis direction.

FIG. 7B is a front view schematically illustrating a deformation stateof the strain body in FIG. 4 when receiving force on a negative side inthe Z-axis direction.

FIG. 8 is a table illustrating changes in capacitance value of eachcapacitative element in the strain body in FIG. 4 .

FIG. 9 is a table illustrating changes in capacitance value of eachcapacitative element in the force sensor in FIG. 5 .

FIG. 10 is a table illustrating main-axis sensitivity and cross-axissensitivity based on the changes in capacitance value in FIG. 9 .

FIG. 11 is a front view illustrating a modification of the strain bodyin FIG. 4 .

FIG. 12 is a plan view illustrating another modification of the strainbody in FIG. 4 .

FIG. 13 is a plan view illustrating another modification of the strainbody in FIG. 4 .

FIG. 14 is a partially enlarged front view illustrating anothermodification of the strain body in FIG. 4 .

FIG. 15 is a partially enlarged front view illustrating anothermodification of the strain body in FIG. 4 .

FIG. 16 is a front view illustrating another modification of the strainbody in FIG. 4 .

FIG. 17 is a front view illustrating another modification of the strainbody in FIG. 4 .

FIG. 18 is a front view illustrating another modification of the strainbody in FIG. 4 .

FIG. 19 is a plan view illustrating another modification of the forcesensor in FIG. 3 .

FIG. 20 is a plan view illustrating another modification of the forcesensor in FIG. 3 .

FIG. 21A is a front view of a strain body illustrating a modification ofa detection element in FIG. 4 .

FIG. 21B is a plan view illustrating the detection element in FIG. 21A.

FIG. 21C is a plan view illustrating a modification of FIG. 21B.

FIG. 22A is a view illustrating a Wheatstone bridge circuit for adetection element provided on a first tilting body illustrated in FIG.21A.

FIG. 22B is a view illustrating a Wheatstone bridge circuit for adetection element provided on a second tilting body illustrated in FIG.21A.

FIG. 23A is a schematic view illustrating a deformation state of thestrain body in FIG. 21A when receiving force on the positive side in theX-axis direction.

FIG. 23B is a schematic view illustrating a deformation state of thestrain body in FIG. 21A when receiving force on the positive side in theZ-axis direction.

FIG. 24 is a front view illustrating a strain body of a force sensor ina second embodiment.

FIG. 25 is a front view schematically illustrating a deformation stateof the strain body in FIG. 24 when receiving force on a positive side inan X-axis direction.

FIG. 26A is a front view schematically illustrating a deformation stateof the strain body in FIG. 24 when receiving force on a positive side ina Z-axis direction.

FIG. 26B is a front view schematically illustrating a deformation stateof the strain body in FIG. 24 when receiving force on a negative side ina Z-axis direction.

FIG. 27 is a plan view illustrating a modification of the strain body inFIG. 24 .

FIG. 28 is a plan view illustrating another modification of the strainbody in FIG. 24 .

FIG. 29 is a plan view illustrating another modification of the strainbody in FIG. 24 .

FIG. 30 is a plan view illustrating another modification of the strainbody in FIG. 24 .

FIG. 31 is a plan view illustrating another modification of the strainbody in FIG. 24 .

DETAILED DESCRIPTION

Embodiments of the present invention will be described below withreference to the drawings. It should be noted that in the drawingsaccompanying the present specification, scale, a lengthwise andcrosswise dimensional ratio, and others are suitably modified andexaggerated from real ones for convenience of illustration and ease ofunderstanding.

It should be noted that terms such as “parallel”, “orthogonal”, and“equal”, dimensions, values of physical properties, and others that areused in the present specification and that specify shapes, geometricalconditions, and physical properties, as well as the degrees thereof arenot restricted by strict meanings, and interpreted inclusive of rangesof degrees at which similar functions can be expected.

First Embodiment

First, a force sensor in a first embodiment of the present invention isdescribed by use of FIGS. 1 to 23B.

Before describing the force sensor according to the present embodiment,an example of applying the force sensor to a robot is described withreference to FIG. 1 . FIG. 1 is a view illustrating one example of arobot to which the force sensor in the present embodiment is applied.

As illustrated in FIG. 1 , an industrial robot 1000 includes a robotmain body 1100, an end effector 1200, an electric cable 1300, acontroller 1400, and a force sensor 1. The robot main body 1100 includesan arm portion of the robot. The force sensor 1 is provided between therobot main body 1100 and the end effector 1200.

The electric cable 1300 extends inside the robot main body 1100. Theelectric cable 1300 is connected to a connector (not illustrated) of theforce sensor 1.

It should be noted that the controller 1400 is disposed inside the robotmain body 1100 in FIG. 1 , but may be disposed in any other place (e.g.,a control board outside the robot). Moreover, the form of attaching theforce sensor 1 to the robot is not limited to the form illustrated inFIG. 1 .

The force sensor 1 detects force or moment acting on the end effector1200 that functions as a gripper. An electric signal indicating thedetected force or moment is transmitted to the controller 1400 of theindustrial robot 1000 via the electric cable 1300. The controller 1400controls the operations of the robot main body 1100 and the end effector1200 on the basis of the received electric signal.

It should be noted that the force sensor 1 is not limited to industrialrobots, and is applicable to various robots such as collaborativerobots, life support robots, medical robots, and service robots.

The force sensor according to the embodiment of the present invention isdescribed below with reference to FIGS. 2 to 5 . FIG. 2 is a sectionalview illustrating the force sensor in the first embodiment, and is aview corresponding to a section along the line A-A in FIG. 3 . FIG. 3 isa plan view illustrating the force sensor in FIG. 2 . FIG. 4 is a frontview illustrating a strain body in FIG. 2 . FIG. 5 is a view in whichthe strain body of the force sensor illustrated in FIG. 3 is developedin a plane.

The following description is given in a situation where an XYZthree-dimensional coordinate system is defined, a Z-axis direction(corresponding to first direction) is a vertical direction, and theforce sensor 1 is disposed in such a way that a force receiving body 10is disposed on an upper side and a support body 20 is disposed on alower side. Thus, the force sensor 1 in the present embodiment is notexclusively used in a posture with the Z-axis direction as a verticaldirection. The force receiving body 10 and the support body 20 may bedisposed on either the upper side or the lower side, respectively.

The force sensor 1 has a function of outputting, as an electric signal,force acting in a predetermined axial direction and moment (or torque)acting around a predetermined rotation axis. However, without beinglimited thereto, the force sensor 1 may be configured to output eitherone of the force and moment as an electric signal, and may be furtherconfigured to output an axis component of at least one of the force andmoment as an electric signal.

As Illustrated in FIGS. 2 and 3 , the force sensor 1 includes the forcereceiving body 10, the support body 20, strain bodies 30A to 30D, adetection element 50, a detection circuit 60, and an exterior body 80.Each component is described in more detail below.

The force receiving body 10 receives action of force or moment to betargeted for detection. By receiving the action, the force receivingbody 10 moves relative to the support body 20. In the case of theexample of FIG. 1 described above, the force receiving body 10 is fixedto the end effector 1200 by a bolt or the like, and receives force ormoment from the end effector 1200. The strain bodies 30A to 30D areconnected to the force receiving body 10.

As illustrated in FIG. 3 , in the present embodiment, the planar shapeof the force receiving body 10 is circular. The force receiving body 10may be formed into a flat-plate shape.

As illustrated in FIG. 2 , the support body 20 supports the forcereceiving body 10. The support body 20 is disposed on a negative side ofthe force receiving body 10 in the Z-axis direction. The force receivingbody 10 and the support body 20 are disposed at positions different fromeach other in the Z-axis direction, and the support body 20 is apartfrom the force receiving body 10. In the case of the example of FIG. 1 ,the support body 20 is fixed to the tip of the robot main body 1100 (orarm portion) by a bolt or the like, and supported by the robot main body1100. The strain bodies 30A to 30D are connected to the support body 20.

As illustrated in FIG. 3 , in the present embodiment, the planar shapeof the support body 20 is circular, as in the force receiving body 10.The support body 20 may be formed into a flat-plate shape. It should benoted that at least one of the planar shape of the force receiving body10 and the planar shape of the support body 20 may be circular. In thiscase, one of the planar shape of the force receiving body 10 and theplanar shape of the support body 20 may be circular, and the other mayhave a shape other than a circular shape.

As illustrated in FIGS. 2 and 3 , the strain bodies 30A to 30D connectthe force receiving body 10 and the support body 20. More specifically,the strain bodies 30A to 30D are disposed between the force receivingbody 10 and the support body 20, and are connected to the forcereceiving body 10 and also connected to the support body 20. The forcereceiving body 10 is supported by the support body 20 via the strainbodies 30A to 30D.

In the present embodiment, the force receiving body 10 and the supportbody 20 are connected to each other by the four strain bodies 30A to30D. The four strain bodies 30A to 30D include a first strain body 30A,a second strain body 30B, a third strain body 30C, and a fourth strainbody 30D. As illustrated in FIG. 3 , when viewed in the Z-axisdirection, the first strain body 30A is disposed on a negative side in aY-axis direction relative to a center O of the force receiving body 10.Similarly, when viewed in the Z-axis direction, the second strain body30B is disposed on a positive side in an X-axis direction relative tothe center O of the force receiving body 10, and the third strain body30C is disposed on a positive side in the Y-axis direction relative tothe center O of the force receiving body 10. The fourth strain body 30Dis disposed on the negative side in the X-axis direction relative to thecenter O of the force receiving body 10. In other words, the center O ofthe force receiving body 10 is disposed between the first strain body30A and the third strain body 30C, and the center O of the forcereceiving body 10 is disposed between the second strain body 30B and thefourth strain body 30D. It should be noted that the number of strainbodies connecting the force receiving body 10 and the support body 20 isnot limited to four but may be two or three, may be five or more, andmay be any number. The force receiving body 10 and the support body 20may be connected by only one strain body. In this case, if the detectionelement 50 comprises two capacitative elements as illustrated in FIG.4A, two axis components of force can be detected. The detection element50 may comprise only one capacitative element, and detect one axiscomponent of force.

As illustrated in FIG. 3 , tilting structures 31 (described later) ofthe four strain bodies 30A to 30D according to the present embodimentare annularly disposed. Specifically, as described above, the forcereceiving body 10 and the support body 20 are formed with a circularshape when viewed in the Z-axis direction, and the four strain bodies30A to 30D are disposed so that the tilting structures 31 form arectangular annular shape. The tilting structure 31 of each of thestrain bodies 30A to 30D is linearly formed along a second directionwhen viewed in the Z-axis direction. Specifically, the second directionof the first strain body 30A and the second direction of the thirdstrain body 30C correspond to the X-axis direction. The tiltingstructure 31 of the first strain body 30A and the tilting structure 31of the third strain body 30C are linearly formed along the X-axisdirection. The second direction of the second strain body 30B and thesecond direction of the fourth strain body 30D correspond to the Y-axisdirection. The tilting structure 31 of the second strain body 30B andthe tilting structure 31 of the fourth strain body 30D are linearlyformed along the Y-axis direction. It should be noted that the fourstrain bodies 30A to 30D are not exclusively annularly disposed, and maybe each disposed at any position irregularly.

Next, the strain bodies 30A to 30D according to the present embodimentare more specifically described. The strain bodies 30A to 30D accordingto the present embodiment are configured to produce strain and causedisplacement by being elastically deformed by the action of force ormoment received by the force receiving body 10. Here, the first strainbody 30A with the X-axis direction as the second direction is describedby way of example among the four strain bodies 30A to 30D describedabove. The second strain body 30B, the third strain body 30C, and thefourth strain body 30D have similar structures, for which detaileddescription is therefore omitted here.

As illustrated in FIGS. 2 and 4 , the first strain body 30A includes thetilting structure 31 disposed between the force receiving body 10 andthe support body 20, a force-receiving-body-side deformable body 33connecting the force receiving body 10 and the tilting structure 31, anda support-body-side deformable body 34 connecting the tilting structure31 and the support body 20.

The tilting structure 31 includes a first tilting body 35 that isdisposed in a plane (corresponding to XZ plane) including the Z-axisdirection and the X-axis direction (corresponding to the seconddirection of the first strain body 30A) orthogonal to the Z-axisdirection and that extends in a direction different from the Z-axisdirection. The first tilting body 35 according to the present embodimentextends in the X-axis direction (corresponding to the second directionof the first strain body 30A). The first tilting body 35 is disposedbetween the force receiving body 10 and the support body 20, and isapart from the force receiving body 10 and also apart from the supportbody 20. In the present embodiment, the first tilting body 35 extends inthe X-axis direction. More specifically, as illustrated in FIG. 4 , thefirst tilting body 35 linearly extends in the X-axis direction from oneend 35 a of the first tilting body 35 to the other end 35 b, and acentral portion 35 c of the first tilting body 35 in the X-axisdirection is located at the same position in the Z-axis direction asboth the ends 35 a and 35 b. The entire surface of the first tiltingbody 35 on the side of the force receiving body 10 is formed into a flatshape.

In the present embodiment, as illustrated in FIGS. 2 and 4 , the tiltingstructure 31 further includes a second tilting body 36 disposed betweenthe first tilting body 35 and the support body 20, and a pair ofconnecting bodies 37 and 38 connecting the first tilting body 35 and thesecond tilting body 36.

The tilting structure 31 includes the second tilting body 36 that isdisposed in the plane (corresponding to XZ plane) including the Z-axisdirection and the X-axis direction (corresponding to the seconddirection of the first strain body 30A) orthogonal to the Z-axisdirection and that extends in a direction different from the Z-axisdirection. The second tilting body 36 according to the presentembodiment extends in the X-axis direction. The second tilting body 36is apart from the first tilting body 35 and also apart from the supportbody 20 in the Z-axis direction. In the present embodiment, the secondtilting body 36 extends in the X-axis direction. More specifically, asillustrated in FIG. 4 , the second tilting body 36 linearly extends inthe X-axis direction from one end 36 a of the second tilting body 36 tothe other end 36 b, and a central portion 36 c of the second tiltingbody 36 in the X-axis direction is located at the same position in theZ-axis direction as both the ends 36 a and 36 b. The entire surface ofthe second tilting body 36 on the side of the force receiving body 10 isformed into a flat shape.

The pair of connecting bodies 37 and 38 connect either one of the bothends 35 a and 35 b of the first tilting body 35 in the X-axis directionand a corresponding one of the both ends 36 a and 36 b of the secondtilting body 36 in the X-axis direction. More specifically, asillustrated in FIG. 4 , the connecting body 37 disposed on the negativeside in the X-axis direction connects the end 35 a of the first tiltingbody 35 on the negative side in the X-axis direction and the end 36 a ofthe second tilting body 36 on the negative side in the X-axis direction.The connecting body 38 disposed on the positive side in the X-axisdirection connects the end 35 b of the first tilting body 35 on thepositive side in the X-axis direction and the end 36 b of the secondtilting body 36 on the positive side in the X-axis direction. Each ofthe connecting bodies 37 and 38 extends in the Z-axis direction.

Thus, the tilting structure 31 according to the present embodiment isformed into a rectangular frame shape as illustrated in FIG. 4 whenviewed in the Y-axis direction (corresponding to a direction orthogonalto the Z-axis direction and the X-axis direction).

The first tilting body 35 is elastically deformable by the action offorce in the Z-axis direction. The second tilting body 36 is elasticallydeformable by the action of force in the Z-axis direction. The springconstant of the first tilting body 35 relative to force acting in theZ-axis direction may be equal to the spring constant of the secondtilting body 36 relative to force acting in the Z-axis direction. Thespring constant can be adjusted mainly by the dimension of a member inthe Z-axis direction, or the type of material to be used. For example,the spring constant may be adjusted as in a first modificationillustrated in FIG. 11 described later.

The force-receiving-body-side deformable body 33 extends in the Z-axisdirection, and is connected to the first tilting body 35 of the tiltingstructure 31. More specifically, the force-receiving-body-sidedeformable body 33 has an upper end connected to the force receivingbody 10, and a lower end connected to the first tilting body 35. Thus,the force receiving body 10 and the first tilting body 35 are connectedby one force-receiving-body-side deformable body 33. In the presentembodiment, the force-receiving-body-side deformable body 33 is locatedbetween both the ends 35 a and 35 b of the first tilting body 35 in theX-axis direction. Specifically, the force-receiving-body-side deformablebody 33 is located between the pair of connecting bodies 37 and 38. Morespecifically, the force-receiving-body-side deformable body 33 islocated in the center of the first tilting body 35 in the X-axisdirection, and is connected to the central portion 35 c of the firsttilting body 35.

The support-body-side deformable body 34 extends in the Z-axisdirection, and is connected to the second tilting body 36 of the tiltingstructure 31. More specifically, the support-body-side deformable body34 has a lower end connected to the support body 20 and an upper endconnected to the second tilting body 36. Thus, the support body 20 andthe second tilting body 36 are connected by one support-body-sidedeformable body 34. In the present embodiment, the support-body-sidedeformable body 34 is located between both the ends 36 a and 36 b of thesecond tilting body 36 in the X-axis direction. Specifically, thesupport-body-side deformable body 34 is located between the pair ofconnecting bodies 37 and 38. More specifically, the support-body-sidedeformable body 34 is located in the center of the second tilting body36 in the X-axis direction, and is connected to the central portion 36 cof the second tilting body 36.

The force-receiving-body-side deformable body 33 and thesupport-body-side deformable body 34 are disposed at positionsoverlapping each other when viewed in the Z-axis direction.Specifically, the force-receiving-body-side deformable body 33 and thesupport-body-side deformable body 34 are disposed at the same positionin the X-axis direction. In the present embodiment, theforce-receiving-body-side deformable body 33 and the support-body-sidedeformable body 34 are disposed in the center of the tilting structure31 in the X-axis direction. Thus, the tilting structure 31 is formedsymmetrically with respect to the force-receiving-body-side deformablebody 33 and the support-body-side deformable body 34 in the X-axisdirection.

The force-receiving-body-side deformable body 33 is elasticallydeformable by the action of force or moment received by the forcereceiving body 10. The force-receiving-body-side deformable body 33 maybe elastically deformable mainly in response to force acting in theX-axis direction. The spring constant of the force-receiving-body-sidedeformable body 33 relative to force acting in the X-axis direction maybe lower than the spring constant of the connecting bodies 37 and 38relative to force acting in the X-axis direction.

The support-body-side deformable body 34 is elastically deformable bythe action of force or moment received by the force receiving body 10.The support-body-side deformable body 34 may be elastically deformablemainly in response to force acting in the X-axis direction. The springconstant of the support-body-side deformable body 34 relative to forceacting in the X-axis direction may be lower than the spring constant ofthe connecting bodies 37 and 38 relative to force acting in the X-axisdirection. The spring constant of the support-body-side deformable body34 relative to force acting in the X-axis direction may be equal to thespring constant of the force-receiving-body-side deformable body 33relative to force acting in the X-axis direction.

The first strain body 30A configured as above may be formed by machiningfrom a plate material manufactured by a metal material such as analuminum alloy or an iron alloy or the like, or may be formed bycasting. When formed by machining, the tilting structure 31, theforce-receiving-body-side deformable body 33, and the support-body-sidedeformable body 34 are formed into a plate shape in such a way that theY-axis direction is a thickness direction, and are integrally formedfrom a continuous plate material. This enables the first strain body 30Ato be easily manufactured. The first strain body 30A formed as above maybe fixed to each of the force receiving body 10 and the support body 20by a bolt, adhesive, or the like. Alternatively, the force receivingbody 10, the support body 20, and the strain bodies 30A to 30D may beintegrally formed from a continuous block material by machining (e.g.,cutting), or may be formed by casting.

The detection element 50 is configured to detect displacement caused byelastic deformation produced in the first strain body 30A describedabove. The detection element 50 according to the present embodiment isconfigured as an element that detects capacitance. As illustrated inFIG. 4 , the detection element 50 includes a fixed electrode substrateprovided on the support body 20 or the force receiving body 10, and adisplacement electrode substrate provided on the tilting structure 31.In the example illustrated in FIG. 4 , the detection element 50 includestwo fixed electrode substrates Ef1 and Ef2 and two displacementelectrode substrates Ed1 and Ed2, as electrodes for the first strainbody 30A.

The two fixed electrode substrates Ef1 and Ef2 include a first fixedelectrode substrate Ef1 disposed on the negative side in the X-axisdirection and a second fixed electrode substrate Ef2 disposed on thepositive side in the X-axis direction. In the present embodiment, thefixed electrode substrates Ef1 and Ef2 are provided on the surface ofthe support body 20 on the side of the force receiving body 10. Thefixed electrode substrates Ef1 and Ef2 may be joined to the surface ofthe support body 20 on the side of the force receiving body 10 byadhesive, or may be fixed thereto by a bolt or the like. The fixedelectrode substrates Ef1 and Ef2 each include a fixed electrode Effacing the corresponding displacement electrode substrates Ed1 and Ed2and an insulator IBf (see FIG. 4 ) interposed between the fixedelectrode Ef and the support body 20. It should be noted that the fixedelectrode substrates Ef1 and Ef2 may be provided on the surface of theforce receiving body 10 on the side of the support body 20.

The two displacement electrode substrates Ed1 and Ed2 include a firstdisplacement electrode substrate Ed1 disposed on the negative side inthe X-axis direction and a second displacement electrode substrate Ed2disposed on the positive side in the X-axis direction. In the presentembodiment, the displacement electrode substrates Ed1 and Ed2 areprovided on the surface of the second tilting body 36 of the tiltingstructure 31 on the side of the support body 20. The displacementelectrode substrates Ed1 and Ed2 may be joined to the surface of thesecond tilting body 36 on the side of the support body 20 by adhesive,or may be fixed thereto by a bolt or the like. The displacementelectrode substrates Ed1 and Ed2 each include a displacement electrodeEd facing the corresponding fixed electrode substrates Ef1 and Ef2 andan insulator IBd (see FIG. 4 ) interposed between the displacementelectrode Ed and the second tilting body 36. It should be noted thatwhen the fixed electrode substrates Ef1 and Ef2 are provided on thesurface of the force receiving body 10 on the side of the support body20, the displacement electrode substrates Ed1 and Ed2 may be provided onthe surface of the first tilting body 35 of the tilting structure 31 onthe side of the force receiving body 10.

The first fixed electrode substrate Ef1 faces the first displacementelectrode substrate Ed1, and the second fixed electrode substrate Ef2faces the second displacement electrode substrate Ed2. A firstcapacitative element C1 is constituted of the first fixed electrodesubstrate Ef1 and the first displacement electrode substrate Ed1, and asecond capacitative element C2 is constituted of the second fixedelectrode substrate Ef2 and the second displacement electrode substrateEd2. The first capacitative element C1 and the second capacitativeelement C2 are configured as the detection element 50 for the firststrain body 30A.

The first displacement electrode substrate Ed1 and the seconddisplacement electrode substrate Ed2 are disposed at positions differentfrom each other in the X-axis direction. In the present embodiment, thefirst displacement electrode substrate Ed1 is disposed on the negativeside in the X-axis direction with respect to the support-body-sidedeformable body 34, and the second displacement electrode substrate Ed2is disposed on the positive side in the X-axis direction with respect tothe support-body-side deformable body 34. When the dimension of thetilting structure 31 (or the second tilting body 36) in the X-axisdirection is L, the displacement electrode substrates Ed1 and Ed2 may bedisposed within a range of L/4 or more and L/2 or less from the centerof the tilting structure 31 in the X-axis direction.

In the present embodiment, the displacement electrode substrates Ed1 andEd2 are disposed at both ends of the tilting structure 31 in the X-axisdirection. More specifically, the first displacement electrode substrateEd1 is disposed at the end 36 a on the negative side in the X-axisdirection of the second tilting body 36, and the second displacementelectrode substrate Ed2 is disposed at the end 36 b on the positive sidein the X-axis direction of the second tilting body 36 of the tiltingstructure 31.

The first fixed electrode substrate Ef1 is disposed at the positionfacing the first displacement electrode substrate Ed1, and is disposedbelow the first displacement electrode substrate Ed1. The second fixedelectrode substrate Ef2 is disposed at the position facing the seconddisplacement electrode substrate Ed2, and is disposed below the seconddisplacement electrode substrate Ed2.

The first capacitative element C1 and the second capacitative element C2are disposed at the same position in the Y-axis direction. Specifically,the first displacement electrode substrate Ed1 and the seconddisplacement electrode substrate Ed2 are disposed at the same positionin the Y-axis direction, and the first fixed electrode substrate Ef1 andthe second fixed electrode substrate Ef2 are also disposed at the sameposition in the Y-axis direction.

In the present embodiment, the planar shapes of the fixed electrodesubstrates Ef1 and Ef2 are rectangular. The planar shapes of thedisplacement electrode substrates Ed1 and Ed2 are also rectangular.However, the planar shapes of the fixed electrode substrates Ef1 and Ef2and the displacement electrode substrates Ed1 and Ed2 are notexclusively rectangular, and may be any other shape, such as a circular,polygonal, or elliptical shape.

When viewed in the Z-axis direction, the first fixed electrode substrateEf1 may be larger than the first displacement electrode substrate Ed1.For example, the planar shape of the first fixed electrode substrate Ef1may be larger than the planar shape of the first displacement electrodesubstrate Ed1. The first displacement electrode substrate Ed1 mayoverlap the first fixed electrode substrate Ef1 as a whole when viewedin the Z-axis direction even when the first displacement electrodesubstrate Ed1 is displaced in the X-axis direction, the Y-axisdirection, or the Z-axis direction. In other words, the size of thedisplacement electrode Ed and the size of the fixed electrode Ef may beset so that the displacement electrode Ed and the fixed electrode Efconstituting the first capacitative element C1 overlap even when thefirst displacement electrode substrate Ed1 is displaced in the X-axisdirection, the Y-axis direction, and the Z-axis direction. Thus, evenwhen the first displacement electrode substrate Ed1 is displaced,changing of the facing area of the displacement electrode Ed and thefixed electrode Ef can be prevented, and an influence of a change in thefacing area on a change in capacitance value can also be prevented.Thus, a capacitance value can be changed in accordance with a change inthe distance between the displacement electrode Ed and the fixedelectrode Ef. Here, the facing area refers to an area in which thedisplacement electrode Ed and the fixed electrode Ef overlap when viewedin the Z-axis direction. When the tilting structure 31 is tilted, thedisplacement electrode Ed smaller than the fixed electrode Ef inclines,and the facing area can vary, but the tilting angle of the displacementelectrode Ed in this case is small. As a result, the distance betweenthe displacement electrode Ed and the fixed electrode Ef dominates achange in capacitance value. Thus, in the present specification,variation of the facing area due to the inclination of the displacementelectrode Ed is not considered, and a change in capacitance value isconsidered to be attributed to a change in the distance between thedisplacement electrode Ed and the fixed electrode Ef. It should be notedthat in FIG. 6 and others described later, inclination of the tiltingstructure 31 is exaggerated for clarity of the drawing. The planar shapeof the first fixed electrode substrate Ef1 is not exclusively largerthan the planar shape of the first displacement electrode substrate Ed1,and the planar shape of the first displacement electrode substrate Ed1may be larger than the planar shape of the first fixed electrodesubstrate Ef1.

Similarly, the planar shape of the second fixed electrode substrate Ef2may be larger than the planar shape of the second displacement electrodesubstrate Ed2 when viewed in the Z-axis direction. It should be notedthat the planar shape of the second displacement electrode substrate Ed2may be larger than the planar shape of the second fixed electrodesubstrate Ef2.

The planar shape of the fixed electrode Ef and the planar shape of theinsulator IBf of each of the fixed electrode substrates Ef1 and Ef2 mayhave the same size. However, without being limited thereto, the planarshape of the fixed electrode Ef and the planar shape of the insulatorIBf may have sizes different from each other. The same also applies tothe planar shape of the displacement electrode Ed and the planar shapeof the insulator IBd of each of the displacement electrode substratesEd1 and Ed2.

The first fixed electrode substrate Ef1 and the second fixed electrodesubstrate Ef2 may be separately formed and apart from each other asillustrated in FIG. 4 . However, without being limited thereto, thefirst fixed electrode substrate Ef1 and the second fixed electrodesubstrate Ef2 may be integrated and configured by one common fixedelectrode substrate. Alternatively, when the first fixed electrodesubstrate Ef1 and the second fixed electrode substrate Ef2 areseparately formed, the first displacement electrode substrate Ed1 andthe second displacement electrode substrate Ed2 may be integrated andconfigured by one common displacement electrode substrate.

The configurations of the first strain body 30A and the correspondingdetection element 50 described above are also applicable to the secondstrain body 30B, the third strain body 30C, and the fourth strain body30D.

Specifically, as illustrated in FIG. 5 , the detection element 50further includes, as electrodes for the second strain body 30B, twofixed electrode substrates Ef3 and Ef4 provided on the support body 20,and two displacement electrode substrates Ed3 and Ed4 provided on thesecond tilting body 36 of the tilting structure 31. The two fixedelectrode substrates Ef3 and Ef4 include a third fixed electrodesubstrate Ef3 and a fourth fixed electrode substrate Ef4. The twodisplacement electrode substrates Ed3 and Ed4 include a thirddisplacement electrode substrate Ed3 and a fourth displacement electrodesubstrate Ed4. The third fixed electrode substrate Ef3 faces the thirddisplacement electrode substrate Ed3, and the fourth fixed electrodesubstrate Ef4 faces the fourth displacement electrode substrate Ed4. Athird capacitative element C3 is constituted of the third fixedelectrode substrate Ef3 and the third displacement electrode substrateEd3, and a fourth capacitative element C4 is constituted of the fourthfixed electrode substrate Ef4 and the fourth displacement electrodesubstrate Ed4.

The third displacement electrode substrate Ed3 and the third fixedelectrode substrate Ef3 are disposed on the negative side in the Y-axisdirection with respect to the support-body-side deformable body 34. Thefourth displacement electrode substrate Ed4 and the fourth fixedelectrode substrate Ef4 are disposed on the positive side in the Y-axisdirection with respect to the support-body-side deformable body 34. Thethird capacitative element C3 and the fourth capacitative element C4 aredisposed at the same position in the X-axis direction. The fixedelectrode substrates Ef3 and Ef4 have a configuration similar to that ofthe fixed electrode substrates Ef1 and Ef2 described above. Thedisplacement electrode substrates Ed3 and Ed4 have a configurationsimilar to that of the displacement electrode substrates Ed1 and Ed2described above.

The detection element 50 further includes, as electrodes for the thirdstrain body 30C, two fixed electrode substrates Ef5 and Ef6 provided onthe support body 20, and two displacement electrode substrates Ed5 andEd6 provided on the second tilting body 36 of the tilting structure 31.The two fixed electrode substrates Ef5 and Ef6 include a fifth fixedelectrode substrate Ef5 and a sixth fixed electrode substrate Ef6. Thetwo displacement electrode substrates Ed5 and Ed6 include a fifthdisplacement electrode substrate Ed5 and a sixth displacement electrodesubstrate Ed6. The fifth fixed electrode substrate Ef5 faces the fifthdisplacement electrode substrate Ed5, and the sixth fixed electrodesubstrate Ef6 faces the sixth displacement electrode substrate Ed6. Afifth capacitative element C5 is constituted of the fifth fixedelectrode substrate Ef5 and the fifth displacement electrode substrateEd5, and a sixth capacitative element C6 is constituted of the sixthfixed electrode substrate Ef6 and the sixth displacement electrodesubstrate Ed6.

The fifth displacement electrode substrate Ed5 and the fifth fixedelectrode substrate Ef5 are disposed on the positive side in the X-axisdirection with respect to the support-body-side deformable body 34. Thesixth displacement electrode substrate Ed6 and the sixth fixed electrodesubstrate Ef6 are disposed on the negative side in the X-axis directionwith respect to the support-body-side deformable body 34. The fifthcapacitative element C5 and the sixth capacitative element C6 aredisposed at the same position in the Y-axis direction. The fixedelectrode substrates Ef5 and Ef6 have a configuration similar to that ofthe fixed electrode substrates Ef1 and Ef2 described above. Thedisplacement electrode substrates Ed5 and Ed6 have a configurationsimilar to that of the displacement electrode substrates Ed1 and Ed2described above.

The detection element 50 further includes, as electrodes for the fourthstrain body 30D, two fixed electrode substrates Ef7 and Ef8 provided onthe support body 20, and two displacement electrode substrates Ed7 andEd8 provided on the second tilting body 36 of the tilting structure 31.The two fixed electrode substrates Ef7 and Ef8 include a seventh fixedelectrode substrate Ef7 and an eighth fixed electrode substrate Ef8. Thetwo displacement electrode substrates Ed7 and Ed8 include a seventhdisplacement electrode substrate Ed7 and an eighth displacementelectrode substrate Ed8. The seventh fixed electrode substrate Ef7 facesthe seventh displacement electrode substrate Ed7, and the eighth fixedelectrode substrate Ef8 faces the eighth displacement electrodesubstrate Ed8. A seventh capacitative element C7 is constituted of theseventh fixed electrode substrate Ef7 and the seventh displacementelectrode substrate Ed7, and an eighth capacitative element C8 isconstituted of the eighth fixed electrode substrate Ef8 and the eighthdisplacement electrode substrate Ed8.

The seventh displacement electrode substrate Ed7 and the seventh fixedelectrode substrate Ef7 are disposed on the positive side in the Y-axisdirection with respect to the support-body-side deformable body 34. Theeighth displacement electrode substrate Ed8 and the eighth fixedelectrode substrate Ef8 are disposed on the negative side in the Y-axisdirection with respect to the support-body-side deformable body 34. Theseventh capacitative element C7 and the eighth capacitative element C8are disposed at the same position in the X-axis direction. The fixedelectrode substrates Ef7 and Ef8 have a configuration similar to that ofthe fixed electrode substrates Ef1 and Ef2 described above. Thedisplacement electrode substrates Ed7 and Ed8 have a configurationsimilar to that of the displacement electrode substrates Ed1 and Ed2described above.

Each of the fixed electrode substrates Ef1 to Ef8 described above may bea ceramic substrate, glass epoxy substrate, or FPC board (or flexibleprinted circuit board) in which electrode materials are stacked. The FPCboard is a flexible printed circuit board formed into a thin film shape,and may be wholly joined to the support body 20. Each of the fixedelectrode substrates Ef1 to Ef8 may be bonded to the support body 20 byadhesive. The same also applies to each of the displacement electrodesubstrates Ed1 to Ed8. Each of the displacement electrode substrates Ed1to Ed8 may be bonded to the second tilting body 36 by adhesive.

It should be noted that the detection element 50 is not exclusivelyconfigured as a capacitative element that detects capacitance. Forexample, the detection element 50 may be constituted by a strain gaugethat detects strain produced by the action of force or moment receivedby the force receiving body 10. The detection element 50 may beconstituted by a piezoelectric element that generates a charge whenstrain is produced. Moreover, the detection element 50 may beconstituted by an optical sensor that detects displacement by utilizingreflection of light, a sensor that detects displacement by utilizingeddy current, or a sensor that detects displacement by utilizing Halleffect. Particularly, the optical sensor that utilizes reflection oflight, the sensor that utilizes eddy current, and the sensor thatutilizes Hall effect are similar to a detection principle ofcapacitance, and can therefore easily replace a capacitative elementthat detects capacitance. An example in which the detection element 50is constituted by a strain gauge will be described later.

As illustrated in FIG. 2 , the detection circuit 60 outputs an electricsignal indicating force or moment acting on the strain bodies 30A to 30Don the basis of a detection result by the detection element 50. Thedetection circuit 60 may have a calculation function constituted by, forexample, a microprocessor. The detection circuit 60 may also have an A/Dconversion function of converting an analog signal received from thedetection element 50 described above into a digital signal, or afunction of amplifying a signal. The detection circuit 60 may include aterminal that outputs an electric signal which is transmitted to thecontroller 1400 described above from the terminal via the electric cable1300 (see FIG. 1 ).

As illustrated in FIGS. 2 and 3 , the exterior body 80 is configured tocover the four strain bodies 30A to 30D from the outside when viewed inthe Z-axis direction. The exterior body 80 is a cylindrical housing thatconfigures the force sensor 1. The strain bodies 30A to 30D are housedin the exterior body 80. In the present embodiment, the planar sectionalshape (corresponding to a shape in a section along an XY plane) of theexterior body 80 is a circular frame shape.

As illustrated in FIG. 2 , the exterior body 80 is fixed to the supportbody 20, and is apart from the force receiving body 10. The forcereceiving body 10 is disposed in one opening (corresponding to an upperopening in FIG. 2 ) of the exterior body 80, and the support body 20 isdisposed in the other opening (corresponding to a lower opening in FIG.2 ).

More specifically, the support body 20 is fixed to the exterior body 80in such a way as to close the lower opening of the exterior body 80. Theexterior body 80 may be manufactured integrally with the support body20. On the other hand, a gap is provided between the force receivingbody 10 and the exterior body 80, and the force receiving body 10 isdisplaceable in response to the action of force or moment received fromthe end effector 1200. It should be noted that a cushioning material 81may be interposed in the gap between the force receiving body 10 and theexterior body 80 in order to ensure waterproofness and dustproofness.The cushioning material 81 may be formed of an elastically deformablesoft material such as rubber or a sponge. It should be noted that theexterior body 80 may be manufactured integrally not with the supportbody 20 but with the force receiving body 10. In this case, a gap may beprovided between the exterior body 80 and the support body 20.Alternatively, a part of the exterior body 80 on the side of the forcereceiving body 10 may be manufactured integrally with the forcereceiving body 10, and a part of the exterior body 80 on the side of thesupport body 20 may be manufactured integrally with the support body 20.In this case, the exterior body 80 is configured separately into a parton the side of the force receiving body 10 and a part on the side of thesupport body 20. A gap may be provided between the part on the side ofthe force receiving body 10 and the part on the side of the support body20.

Next, a method of detecting force or moment acting on the force sensor 1in the present embodiment having such a configuration as above isdescribed with reference to FIGS. 6 to 7B. FIG. 6 is a front viewschematically illustrating a deformation state of the strain body inFIG. 4 when receiving force on the positive side in the X-axisdirection. FIG. 7A is a front view schematically illustrating adeformation state of the strain body in FIG. 4 when receiving force onthe positive side in the Z-axis direction. FIG. 7B is a front viewschematically illustrating a deformation state of the strain body inFIG. 4 when receiving force on the negative side in the Z-axisdirection.

When the force receiving body 10 receives the action of force or moment,the force or moment is transmitted to the first to fourth strain bodies30A to 30D. More specifically, the force or moment is transmitted to theforce-receiving-body-side deformable body 33, the tilting structure 31,and the support-body-side deformable body 34, and elastic deformation isproduced in the force-receiving-body-side deformable body 33, thesupport-body-side deformable body 34, and the tilting structure 31. Thiscauses displacement to the tilting structure 31. Thus, the distancebetween each of the fixed electrode substrates Ef1 to Ef8 and each ofthe corresponding displacement electrode substrates Ed1 to Ed8 of thedetection element 50 changes, and the capacitance value of each of thecapacitative elements C1 to C8 changes. The detection element 50 detectsthis change in capacitance value as displacement caused to the strainbodies 30A to 30D. In this case, the change in capacitance value of eachof the capacitative elements C1 to C8 can be different. Thus, thedetection circuit 60 can detect the direction and magnitude of the forceor moment acting on the force receiving body 10, on the basis of thechange in capacitance value of each of the capacitative elements C1 toC8 detected by the detection element 50.

Here, first, the first strain body 30A is taken for example to describechanges in capacitance value of the first capacitative element C1 andthe second capacitative element C2, on which force Fx in the X-axisdirection, force Fy in the Y-axis direction, and force Fz in the Z-axisdirection act.

(When +FX acts)

When the force Fx acts on the first strain body 30A on the positive sidein the X-axis direction, the force-receiving-body-side deformable body33 and the support-body-side deformable body 34 of the first strain body30A are elastically deformed in the X-axis direction as illustrated inFIG. 6 . Since the tilting structure 31 according to the presentembodiment is connected to the force receiving body 10 via oneforce-receiving-body-side deformable body 33 and also connected to thesupport body 20 via one support-body-side deformable body 34, theforce-receiving-body-side deformable body 33 and the support-body-sidedeformable body 34 can be elastically deformed to about the same degree.Moreover, since the first tilting body 35 and the second tilting body 36of the tilting structure 31 according to the present embodiment areconnected via the two connecting bodies 37 and 38 extending in theZ-axis direction, the force-receiving-body-side deformable body 33 andthe support-body-side deformable body 34 can be elastically deformedmore than the connecting bodies 37 and 38. More specifically, the upperend of the force-receiving-body-side deformable body 33 is displaced tothe positive side in the X-axis direction more than the lower end.Accordingly, the force-receiving-body-side deformable body 33 inclinesrelative to the Z-axis direction in such a way as to fall down to thepositive side in the X-axis direction while being elastically deformed.Moreover, the upper end of the support-body-side deformable body 34 isdisplaced to the positive side in the X-axis direction more than thelower end. Accordingly, the support-body-side deformable body 34inclines relative to the Z-axis direction in such a way as to fall downto the positive side in the X-axis direction while being elasticallydeformed. Thus, as illustrated in FIG. 6 , the tilting structure 31(including the first tilting body 35, the second tilting body 36, andthe connecting bodies 37 and 38) can be tilted as a whole. In this case,the tilting structure 31 turns clockwise around the Y-axis when viewedtoward the positive side in the Y-axis direction (when viewed toward thepage surface of FIG. 6 ), and is tilted relative to the Z-axisdirection. In this way, the force-receiving-body-side deformable body 33and the support-body-side deformable body 34 of the first strain body30A can be elastically deformed by the force Fx on the positive side inthe X-axis direction. In the tilting structure 31, minute elasticdeformation can be produced, but no such magnitude of elasticdeformation as the elastic deformation of the force-receiving-body-sidedeformable body 33 and the support-body-side deformable body 34 isproduced. In this case, the end 36 a on the negative side in the X-axisdirection of the second tilting body 36 rises, and the end 36 b on thepositive side in the X-axis direction lowers.

As illustrated in FIG. 6 , when the tilting structure 31 of the firststrain body 30A turns clockwise, the first displacement electrodesubstrate Ed1 moves away from the first fixed electrode substrate Ef1.Accordingly, the inter-electrode distance (corresponding to distance inthe Z-axis direction) between the first displacement electrode substrateEd1 and the first fixed electrode substrate Ef1 increases, and thecapacitance value of the first capacitative element C1 decreases. On theother hand, the second displacement electrode substrate Ed2 moves closerto the second fixed electrode substrate Ef2. Accordingly, theinter-electrode distance between the second displacement electrodesubstrate Ed2 and the second fixed electrode substrate Ef2 decreases,and the capacitance value of the second capacitative element C2increases.

(When −Fx Acts)

Although not illustrated, a phenomenon opposite to the case illustratedin FIG. 6 occurs when the force Fx acts on the first strain body 30A onthe negative side in the X-axis direction. Specifically, the capacitancevalue of the first capacitative element C1 increases, and thecapacitance value of the second capacitative element C2 decreases.

(When +Fy Acts)

When the force Fy acts on the first strain body 30A on the positive sidein the Y-axis direction (not illustrated), the first strain body 30Aturns around the X-axis (corresponding to counterclockwise toward thepositive side in the X-axis direction). Accordingly, the first strainbody 30A is elastically deformed in such a way as to fall down to thepositive side in the Y-axis direction and thus incline relative to theZ-axis direction. Thus, the first strain body 30A is elasticallydeformed in such a way as to bend in the thickness direction. However,as described above, the first capacitative element C1 and the secondcapacitative element C2 are disposed at the same position in the Y-axisdirection. Thus, even though the first strain body 30A turns around theX-axis, the capacitance value increases in a region of the firstcapacitative element C1, and the capacitance value decreases in anotherregion. Therefore, no change in capacitance value appears in the wholefirst capacitative element C1. Similarly, no change in capacitance valueappears in the whole second capacitative element C2.

(When −Fy Acts)

When the force Fy acts on the first strain body 30A on the negative sidein the Y-axis direction as well, no changes in capacitance value appearin the whole first capacitative element C1 and the whole secondcapacitative element C2.

(When +Fz Acts)

When the force Fz acts on the first strain body 30A on the positive sidein the Z-axis direction, the first tilting body 35 and the secondtilting body 36 of the tilting structure 31 are elastically deformed asillustrated in FIG. 7A. More specifically, while the first tilting body35 is elastically deformed, the force-receiving-body-side deformablebody 33 is pulled up to the positive side in the Z-axis direction.Accordingly, the first tilting body 35 is pulled up with theforce-receiving-body-side deformable body 33 in the central portion 35 cof the first tilting body 35 in the X-axis direction as illustrated inFIG. 7A. In this instance, while the first tilting body 35 iselastically deformed in such a way as to project upward (e.g., in aninverted V-shape manner), the connecting bodies 37 and 38 are pulled upto the positive side in the Z-axis direction. Thus, the second tiltingbody 36 is pulled up at both the ends 36 a and 36 b thereof in theX-axis direction as illustrated in FIG. 7A. In this instance, the secondtilting body 36 is elastically deformed in such a way as to projectdownward (e.g., in a V-shape).

As illustrated in FIG. 7A, when the first tilting body 35 and the secondtilting body 36 are elastically deformed, the first displacementelectrode substrate Ed1 moves away from the first fixed electrodesubstrate Ef1. Thus, the capacitance value of the first capacitativeelement C1 decreases. Moreover, the second displacement electrodesubstrate Ed2 moves away from the second fixed electrode substrate Ef2.Thus, the capacitance value of the second capacitative element C2decreases.

(When −Fz Acts)

When the force Fz acts on the first strain body 30A on the negative sidein the Z-axis direction, the first tilting body 35 and the secondtilting body 36 of the tilting structure 31 are elastically deformed asillustrated in FIG. 7B. More specifically, while the first tilting body35 is elastically deformed, the force-receiving-body-side deformablebody 33 is pulled down to the negative side in the Z-axis direction.Accordingly, the first tilting body 35 is pulled down by theforce-receiving-body-side deformable body 33 in the central portion 35 cof the first tilting body 35 in the X-axis direction as illustrated inFIG. 78 . In this instance, while the first tilting body 35 iselastically deformed in such a way as to project downward (e.g., aV-shape), the connecting bodies 37 and 38 are pulled down to thenegative side in the Z-axis direction. Thus, the second tilting body 36is pulled down at both the ends 36 a and 36 b thereof in the X-axisdirection as illustrated in FIG. 7B. In this instance, the secondtilting body 36 is elastically deformed in such a way as to projectupward (e.g., an inverted V-shape).

As illustrated in FIG. 7B, when the first tilting body 35 and the secondtilting body 36 are elastically deformed, the first displacementelectrode substrate Ed1 moves closer to the first fixed electrodesubstrate Ef1. Thus, the capacitance value of the first capacitativeelement C1 increases. Moreover, the second displacement electrodesubstrate Ed2 moves closer to the second fixed electrode substrate Ef2.Thus, the capacitance value of the second capacitative element C2increases.

Here, changes in capacitance value of each of the capacitative elementsC1 and C2 provided on the first strain body 30A illustrated in FIG. 4are shown in FIG. 8 . FIG. 8 is a table showing changes in capacitancevalue of each of the capacitative elements C1 and C2 in the first strainbody 30A in FIG. 4 .

FIG. 8 illustrates changes in capacitance value of the capacitativeelements C1 and C2 with regard to the force Fx in the X-axis direction,the force Fy in the Y-axis direction, and the force Fz in the Z-axisdirection. In FIG. 8 , the case where the capacitance value decreases isindicated by “− (minus)”, and the case where the capacitance valueincreases is indicated by “+(plus)”. For example, “−” is indicated forC1 of the row of Fx in the table illustrated in FIG. 8 , which showsthat the capacitance value of the first capacitative element C1decreases when the force of +Fx acts as described above. On the otherhand, “+” is indicated for C2 of the row of Fx in the table illustratedin FIG. 8 , which shows that the capacitance value of the secondcapacitative element C2 increases when the force of +Fx acts asdescribed above. In FIG. 8 , the numerical value “0 (zero)” indicatesthat no changes in capacitance value of the capacitative elements C1 andC2 appear.

The forces Fx and Fz acting on the force receiving body 10 in the forcesensor 1 in which the force receiving body 10 and the support body 20are connected by only the first strain body 30A can be calculated fromthe table illustrated in FIG. 8 by the following equations. It should benoted that in the following equations, force or moment and a changeamount of a capacitance value are connected by “=” for convenience.However, since force or moment and a capacitance value are physicalquantities different from each other, force is actually calculated byconverting a change amount of a capacitance value. C1 and C2 in thefollowing equations each indicate a change amount of a capacitance valuein each of the capacitative elements.Fx=−C1+C2  [Equation 1]Fz=−C1-C2  [Equation 2]

Next, changes in capacitance value of each of the capacitative elementsC1 to C8 when the force Fx in the X-axis direction, the force Fy in theY-axis direction, the force Fz in the Z-axis direction, moment Mx aroundthe X-axis, moment My around the Y-axis, and moment Mz around the Z-axisact in the force sensor 1 illustrated in FIG. 5 are described withreference to FIGS. 9 and 10 . FIG. 9 is a table illustrating changes incapacitance value of each capacitative element in the force sensor inFIG. 5 . FIG. 10 is a table illustrating main-axis sensitivity andcross-axis sensitivity based on the changes in capacitance value in FIG.9 .

(When +Fx Acts)

First, the case where the force Fx acts on the force receiving body 10on the positive side in the X-axis direction is described.

In this case, the first strain body 30A is elastically deformed in amanner similar to the first strain body 30A illustrated in FIG. 6 , thecapacitance value of the first capacitative element C1 decreases, andthe capacitance value of the second capacitative element C2 increases.This is indicated as “− (minus)” in C1 and indicated as “+ (plus)” in C2of the row of Fx in the table illustrated in FIG. 9 .

The second strain body 30B turns around the Y-axis (corresponding toclockwise toward the positive side in the Y-axis direction). However, asdescribed above, the third capacitative element C3 and the fourthcapacitative element C4 are disposed at the same position in the X-axisdirection. Thus, as in the first strain body 30A on which the force Fyin the Y-axis direction described above acts, no changes in capacitancevalue appear in the entire third capacitative element C3 and the entirefourth capacitative element C4. This is indicated as “0 (zero)” in C3and C4 of the row of Fx in the table illustrated in FIG. 9 .

The third strain body 30C is elastically deformed in a manner similar tothe first strain body 30A illustrated in FIG. 6 . Thus, the capacitancevalue of the fifth capacitative element C5 increases, and thecapacitance value of the sixth capacitative element C6 decreases. Thisis indicated as “+” in C5 and indicated as “−” in C6 of the row of Fx inthe table illustrated in FIG. 9 .

The fourth strain body 30D turns around the Y-axis in a manner similarto the second strain body 30B. However, as described above, the seventhcapacitative element C7 and the eighth capacitative element C8 aredisposed at the same position in the X-axis direction. Thus, no changesin capacitance value appear in the entire seventh capacitative elementC7 and the entire eighth capacitative element C8. This is indicated as“0 (zero)” in C7 and C8 of the row of Fx in the table illustrated inFIG. 9 .

(When +Fy Acts)

Next, the case where the force Fy acts on the force receiving body 10 onthe positive side in the Y-axis direction is described. In the followingdescription as well, signs in the table in FIG. 9 are determined asdescribed above depending on changes in capacitance value.

In this case, the first strain body 30A turns around the X-axis(corresponding to counterclockwise toward the positive side in theX-axis direction). However, as described above, the first capacitativeelement C1 and the second capacitative element C2 are disposed at thesame position in the Y-axis direction. Thus, no changes in capacitancevalue appear in the entire first capacitative element C1 and the entiresecond capacitative element C2.

The second strain body 30B is elastically deformed in a manner similarto the first strain body 30A illustrated in FIG. 6 , the capacitancevalue of the third capacitative element C3 decreases, and thecapacitance value of the fourth capacitative element C4 increases.

The third strain body 30C turns around the X-axis in a manner similar tothe first strain body 30A. However, the fifth capacitative element C5and the sixth capacitative element C6 are disposed at the same positionin the Y-axis direction. Thus, no changes in capacitance value appear inthe entire fifth capacitative element C5 and the entire sixthcapacitative element C6.

The fourth strain body 30D is elastically deformed in a manner similarto the first strain body 30A illustrated in FIG. 6 , the capacitancevalue of the seventh capacitative element C7 increases, and thecapacitance value of the eighth capacitative element C8 decreases.

(When +Fz Acts)

Next, the case where the force Fz acts on the force receiving body 10 onthe positive side in the Z-axis direction is described. In the followingdescription as well, signs in the table in FIG. 9 are determined asdescribed above depending on changes in capacitance value.

In this case, each of the strain bodies 30A to 30D is elasticallydeformed in a manner similar to the first strain body 30A illustrated inFIG. 7A. Accordingly, the capacitance value of each of the capacitativeelements C1 to C8 decreases.

(When +Mx Acts)

Next, the case where the moment Mx (see FIG. 5 ) around the X-axis(corresponding to clockwise toward the positive side in the X-axisdirection) acts on the force receiving body 10 is described. In thefollowing description as well, signs in the table in FIG. 9 aredetermined as described above depending on changes in capacitance value.

In this case, the first strain body 30A is elastically deformed in amanner similar to the first strain body 30A illustrated in FIG. 7B, thecapacitance value of the first capacitative element C1 increases, andthe capacitance value of the second capacitative element C2 increases.

The force-receiving-body-side deformable body 33 is located at thecenter O of the force receiving body 10 in the Y-axis direction in thesecond strain body 30B, and elastic deformation of the second strainbody 30B is therefore smaller than elastic deformation of the firststrain body 30A and the third strain body 30C. Here, for simplificationof description, it is considered that the second strain body 30B is notelastically deformed. Thus, the capacitance value of the thirdcapacitative element C3 does not change, and the capacitance value ofthe fourth capacitative element C4 does not change either.

The third strain body 30C is elastically deformed in a manner similar tothe first strain body 30A illustrated in FIG. 7A, the capacitance valueof the fifth capacitative element C5 decreases, and the capacitancevalue of the sixth capacitative element C6 decreases.

The force-receiving-body-side deformable body 33 is located at thecenter O of the force receiving body 10 in the Y-axis direction in thefourth strain body 30D, and elastic deformation of the fourth strainbody 30D is therefore smaller than elastic deformation of the firststrain body 30A and the third strain body 30C. Here, for simplificationof description, it is considered that the fourth strain body 30D is notelastically deformed. Thus, the capacitance value of the seventhcapacitative element C7 does not change, and the capacitance value ofthe eighth capacitative element C8 does not change either.

(When +My Acts)

Next, the case where the moment My (see FIG. 5 ) around the Y-axis(corresponding to clockwise toward the positive side in the Y-axisdirection) acts on the force receiving body 10 is described. In thefollowing description as well, signs in the table in FIG. 9 aredetermined as described above depending on changes in capacitance value.

In this case, the force-receiving-body-side deformable body 33 islocated at the center O of the force receiving body 10 in the X-axisdirection in the first strain body 30A, and elastic deformation of thefirst strain body 30A is therefore smaller than elastic deformation ofthe second strain body 30B and the fourth strain body 30D. Here, forsimplification of description, it is considered that the first strainbody 30A is not elastically deformed. Thus, the capacitance value of thefirst capacitative element C1 does not change, and the capacitance valueof the second capacitative element C2 does not change either.

The second strain body 30B is elastically deformed in a manner similarto the first strain body 30A illustrated in FIG. 7B, the capacitancevalue of the third capacitative element C3 increases, and thecapacitance value of the fourth capacitative element C4 increases.

The force-receiving-body-side deformable body 33 is located at thecenter O of the force receiving body 10 in the X-axis direction in thethird strain body 30C, and elastic deformation of the third strain body30C is therefore smaller than elastic deformation of the second strainbody 30B and the fourth strain body 30D. Here, for simplification ofdescription, it is considered that the third strain body 30C is notelastically deformed. Thus, the capacitance value of the fifthcapacitative element C5 does not change, and the capacitance value ofthe sixth capacitative element C6 does not change either.

The fourth strain body 30D is elastically deformed in a manner similarto the first strain body 30A illustrated in FIG. 7A, the capacitancevalue of the seventh capacitative element C7 decreases, and thecapacitance value of the eighth capacitative element C8 decreases.

(When +Mz Acts)

Next, the case where the moment Mz (see FIG. 5 ) around the Z-axis(corresponding to clockwise toward the positive side in the Z-axisdirection) acts on the force receiving body 10 is described. In thefollowing description as well, signs in the table in FIG. 9 aredetermined as described above depending on changes in capacitance value.

In this case, the first strain body 30A is elastically deformed as inthe case where the force Fx on the positive side in the X-axis directionacts. Accordingly, the first strain body 30A is elastically deformed ina manner similar to the first strain body 30A illustrated in FIG. 6 ,the capacitance value of the first capacitative element C1 decreases,and the capacitance value of the second capacitative element C2increases.

The second strain body 30B is elastically deformed as in the case wherethe force Fy on the positive side in the Y-axis direction acts.Accordingly, the second strain body 30B is elastically deformed in amanner similar to the first strain body 30A illustrated in FIG. 6 , thecapacitance value of the third capacitative element C3 decreases, andthe capacitance value of the fourth capacitative element C4 increases.

The third strain body 30C is elastically deformed as in the case wherethe force Fx on the negative side in the X-axis direction acts.Accordingly, the capacitance value of the fifth capacitative element C5decreases, and the capacitance value of the sixth capacitative elementC6 increases.

The fourth strain body 30D is elastically deformed as in the case wherethe force Fy on the negative side in the Y-axis direction acts.Accordingly, the capacitance value of the seventh capacitative elementC7 decreases, and the capacitance value of the eighth capacitativeelement C8 increases.

In this way, when a change in capacitance value of each of thecapacitative elements C1 to C8 is detected, the direction and magnitudeof the force or moment acting on the force receiving body 10 isdetected. Then, as illustrated in FIG. 9 , the capacitance value of eachof the capacitative elements C1 to C8 changes.

The forces Fx, Fy, and Fz, and the moments Mx, My, and Mz acting on theforce receiving body 10 can be calculated from the table illustrated inFIG. 9 by the following equations. Thus, six axis components of forcecan be detected. It should be noted that in the following equations,force or moment and a change amount of a capacitance value are connectedby “=” for convenience. However, since force or moment and a capacitancevalue are physical quantities different from each other, force or momentis actually calculated by converting a change amount of a capacitancevalue. C1 to C8 in the following equations each indicate a change amountof a capacitance value in each of the capacitative elements.Fx=−C1+C2+C5−C6  [Equation 3]Fy=−C3+C4+C7−C8  [Equation 4]Fz=−C1−C2−C3−C4−C5−C6−C7−C8  [Equation 5]Mx=+C1+C2−C5−C6  [Equation 6]My=+C3+C4−C7−C8  [Equation 7]Mz=−C1+C2−C3+C4−C5+C6−C7+C8  [Equation 8]

As described above, the force sensor 1 illustrated in FIG. 5 can detectthe forces Fx, Fy, and Fz, and the moments Mx, My, and Mz as indicatedby [Equation 3] to [Equation 8] described above, and is thereforecapable of detecting six axis components of force. However, the forcesensor 1 is not exclusively capable of detecting six axis components offorce, and is capable of detecting any axis components depending on thenumber of strain bodies or the structure and shape of a strain body. Forexample, when the force receiving body 10 and the support body 20 areconnected by only the first strain body 30A illustrated in FIG. 4 , theforce sensor 1 can detect the forces Fx and Fz as indicated by [Equation1] and [Equation 2] described above, and is therefore capable ofdetecting two axis components of force.

If changes in capacitance value of each of the capacitative elements C1to C8 illustrated in FIG. 9 are applied to [Equation 3] to [Equation 8]described above, a table indicating main-axis sensitivity and cross-axissensitivity illustrated in FIG. 10 is obtained. VFx illustrated in FIG.10 is an output when the force Fx in the X-axis direction acts, VFy isan output when the force Fy in the Y-axis direction acts, and VFz is anoutput when the force Fz in the Z-axis direction acts. VMx is an outputwhen the moment Mx around the X-axis direction acts, VMy is an outputwhen the moment My around the Y-axis direction acts, and VMz is anoutput when the moment Mz around the Z-axis direction acts.

The numerical values indicated in the table of FIG. 10 are numericalvalues obtained by substituting “+1” for the capacitative element giventhe sign “+” and “−1” for the capacitative element given the sign “−” onthe right sides of [Equation 3] to [Equation 8] described above, withregard to each of the forces Fx, Fy, and Fz and each of the moments Mx,My, and Mz described on the table of FIG. 9 . For example, the numericalvalue “4” listed in the square where the column of Fx and the row of VFxcross each other is a numerical value obtained by substituting “+1” forC2 and C5, and substituting “−1” for C1 and C6 on the basis of the rowof Fx in FIG. 9 in [Equation 3] indicating Fx. The numerical value “0”listed in the square where the column of Fx and the row of VFy crosseach other is a numerical value obtained by substituting 0 for C1, C2,C5, and C6 on the basis of the row of Fy in FIG. 9 in [Equation 3]indicating Fx.

As illustrated in FIG. 10 , VFx has a numerical value “4” with regard tothe force Fx, whereas VFy, VFz, VMx, VMy, and VMz each have a numericalvalue “0”. Accordingly, with regard to the force Fx, there is nocross-axis sensitivity, and only main-axis sensitivity can be detected.With regard to each of the forces Fy and Fz and each of the moments Mx,My, and Mz as well, there is no cross-axis sensitivity, and onlymain-axis sensitivity can be detected. Specifically, the force sensor 1that can inhibit the occurrence of cross-axis sensitivity can beobtained.

It should be noted that the case where cross-axis sensitivity occurs isalso possible. For example, when the force Fz acts on the positive sidein the Z-axis direction with regard to the first strain body 30A, achange amount of a capacitance value of the first capacitative elementC1 may be different from a change amount of a capacitance value of thesecond capacitative element C2. In this case, cross-axis sensitivity canoccur for the force Fz. When the force Fz and the moments Mx and My acton the force receiving body 10, the first strain body 30A is displacedin the Z-axis direction, so that in the row of Fz, the row of Mx, andthe row of My in the table illustrated in FIG. 9 , change amounts ofcapacitance values may be different even though the same sign is given.In this case, cross-axis sensitivity can occur for the force Fz and themoments Mx and My. Cross-axis sensitivity can occur with regard to theforces Fx and Fy and the moment Mz as well. For example, when the momentMx acts on the force receiving body 10, capacitance value does notchange and the numerical value “0” is therefore listed in the thirdcapacitative element C3, the fourth capacitative element C4, the seventhcapacitative element C7, and the eighth capacitative element C8 asillustrated in FIG. 9 , but capacitance values may change and cross-axissensitivity may occur. The same also applies to the moments My and Mz.

With regard to the capacitative elements for which the numerical value“0” is listed in the rows of Fx and Fy as well, capacitance values maychange, and cross-axis sensitivity may occur.

However, even when cross-axis sensitivity occurs, a correctioncalculation can be performed by deriving an inverse matrix of a matrix(a matrix of six rows and six columns corresponding the tableillustrated in FIG. 10 , also referred to as a characteristic matrix) ofcross-axis sensitivity, and multiplying this inverse matrix by an output(or characteristic matrix) of the force sensor. As a result, cross-axissensitivity can be reduced, and the occurrence of cross-axis sensitivitycan be inhibited.

Thus, according to the present embodiment, each of the strain bodies 30Ato 30D connecting the force receiving body 10 and the support body 20has the tilting structure 31 connected to the force-receiving-body-sidedeformable body 33 and the support-body-side deformable body 34, and thetilting structure 31 includes the first tilting body 35 that is disposedin a plane including the Z-axis direction and the X-axis directionorthogonal to the Z-axis direction and that extends in a directiondifferent from the Z-axis direction. The first tilting body 35 iselastically deformable by the action of force in the Z-axis direction.Accordingly, the tilting structure 31 can be elastically deformed moreeasily by the action of force in the Z-axis direction. Thus,displacement of each of the displacement electrode substrates Ed1 to Ed8can be increased, and detection sensitivity of force or moment can beenhanced. As a result, detection accuracy of the force sensor 1 can beimproved.

According to the present embodiment, the configuration of each of thestrain bodies 30A to 30D can be simplified. Six axis components can bedetected only by connecting at least three strain bodies to the forcereceiving body 10 and the support body 20. Thus, the force sensor 1 canbe lowered in cost.

According to the present embodiment, the force-receiving-body-sidedeformable body 33 extends in the Z-axis direction. Accordingly, whenforce or moment acts on the force receiving body 10, theforce-receiving-body-side deformable body 33 can be elastically deformedmore. Thus, the strain bodies 30A to 30D can be elastically deformedmore easily, and displacement of the displacement electrode substratesEd1 to Ed8 provided on the strain bodies 30A to 30D can be increased.Therefore, detection sensitivity of force or moment can be enhancedmore, and detection accuracy of the force sensor 1 can be improved more.

According to the present embodiment, the support-body-side deformablebody 34 extends in the Z-axis direction. Accordingly, when force ormoment acts on the force receiving body 10, the support-body-sidedeformable body 34 can be elastically deformed more. Thus, the strainbodies 30A to 30D can be elastically deformed more easily, anddisplacement of the displacement electrode substrates Ed1 to Ed8provided on the strain bodies 30A to 30D can be increased. Therefore,detection sensitivity of force or moment can be enhanced more, anddetection accuracy of the force sensor 1 can be improved more.

According to the present embodiment, the first tilting body 35 of eachof the strain bodies 30A to 30D extends in the second direction.Specifically, the first tilting body 35 of each of the strain bodies 30Aand 30C extends in the X-axis direction, and the first tilting body 35of each of the strain bodies 30B and 30D extends in the Y-axisdirection. Accordingly, when receiving the action of force in the Z-axisdirection, the first tilting body 35 can be elastically deformed moreeasily. Thus, displacement of the displacement electrode substrates Ed1to Ed8 can be increased more, and detection sensitivity of force ormoment can be enhanced more.

According to the present embodiment, the force-receiving-body-sidedeformable body 33 is connected to the first tilting body 35, and thesupport-body-side deformable body 34 is connected to the second tiltingbody 36 that is connected to the first tilting body 35 via theconnecting bodies 37 and 38. The second tilting body 36 is elasticallydeformable by the action of force in the X-axis direction. Accordingly,the tilting structure 31 can be elastically deformed more easily by theaction of force in the Z-axis direction. Thus, displacement of each ofthe displacement electrode substrates Ed1 to Ed8 can be increased more,and detection sensitivity of force or moment can be enhanced more. As aresult, detection accuracy of the force sensor 1 can be improved more.

According to the present embodiment, the force-receiving-body-sidedeformable body 33 is located between both the ends 35 a and 35 b of thefirst tilting body 35 in the X-axis direction. Accordingly, the firsttilting body 35 can be elastically deformed more easily by the action offorce in the Z-axis direction. Thus, displacement of each of thedisplacement electrode substrates Ed1 to Ed8 can be increased moreeasily, and detection sensitivity of force or moment can be enhanced.

According to the present embodiment, the support-body-side deformablebody 34 is located between both the ends 36 a and 36 b of the secondtilting body 36 in the X-axis direction. Accordingly, the second tiltingbody 36 can be elastically deformed more easily by the action of forcein the Z-axis direction. Thus, displacement of each of the displacementelectrode substrates Ed1 to Ed8 can be increased more easily, anddetection sensitivity of force or moment can be enhanced.

According to the present embodiment, the force-receiving-body-sidedeformable body 33 and the support-body-side deformable body 34 aredisposed at positions overlapping each other when viewed in the Z-axisdirection. Accordingly, the force-receiving-body-side deformable body 33and the support-body-side deformable body 34 can be disposed at the sameposition in the second direction. Thus, when the force Fz in the Z-axisdirection acts on the force receiving body 10, displacement of the forcereceiving body 10 in a direction (corresponding to the X-axis directionor the Y-axis direction) orthogonal to the Z-axis direction can beinhibited, and the force receiving body 10 can be displaced along theZ-axis direction. In this case, the occurrence of cross-axis sensitivitydescribed above can be inhibited.

According to the present embodiment, the tilting structure 31 is formedsymmetrically with respect to the force-receiving-body-side deformablebody 33 and the support-body-side deformable body 34 in the seconddirection. Accordingly, inclination of the tilting structure 31 can beincreased. Thus, displacement of each of the displacement electrodesubstrates Ed1 to Ed8 can be increased more, and detection sensitivityof force or moment can be enhanced more. When force in the Z-axisdirection acts, displacement of the first displacement electrodesubstrate Ed1 can be equalized to displacement of the seconddisplacement electrode substrate Ed2. Therefore, calculation of force ormoment can be facilitated.

According to the present embodiment, the displacement electrodesubstrates Ed1 to Ed8 of the detection element 50 are disposed at bothends of the tilting structure 31 in the second direction. Accordingly,displacement of each of the displacement electrode substrates Ed1 to Ed8can be increased more, and detection sensitivity of force or moment canbe enhanced more.

According to the present embodiment, the first strain body 30A isdisposed on the negative side in the Y-axis direction relative to thecenter O of the force receiving body 10, the second strain body 30B isdisposed on the positive side in the X-axis direction, the third strainbody 30C is disposed on the positive side in the Y-axis direction, andthe fourth strain body 30D is disposed on the negative side in theX-axis direction. The second direction of the first strain body 30A andthe third strain body 30C is set to the X-axis direction, and the seconddirection of the second strain body 30B and the fourth strain body 30Dis set to the Y-axis direction. Accordingly, when viewed in the Z-axisdirection, the first to fourth strain bodies 30A to 30D can be annularlydisposed relative to the center O of the force receiving body 10.Moreover, the first to fourth strain bodies 30A to 30D can be equallydisposed around the center O of the force receiving body 10. Thus,detection accuracy of force or moment in any direction can be improved,and deterioration in the detection accuracy of force or moment dependingon directions can be inhibited.

According to the present embodiment, the planar shape of the forcereceiving body 10 and the planar shape of the support body 20 arecircular. Accordingly, the force receiving body 10 and the support body20 can be formed along the shape of the arm portion of the robot mainbody 1100 and the end effector 1200.

According to the present embodiment, the tilting structure 31 of each ofthe strain bodies 30A to 30D is linearly formed along the seconddirection when viewed in the Z-axis direction. Accordingly, the tiltingstructure 31 can be formed into a plate shape. For example, the tiltingstructure 31 can be easily manufactured from a plate material.

(First Modification)

It should be noted that in the example described above in the presentembodiment, the spring constant of the first tilting body 35 relative toforce acting in the Z-axis direction is equal to the spring constant ofthe second tilting body 36 relative to force acting in the Z-axisdirection. However, without being limited thereto, the spring constantof the second tilting body 36 relative to force acting in the Z-axisdirection may be different from the spring constant of the first tiltingbody 35 relative to force acting in the Z-axis direction, for example,as illustrated in FIG. 11 . For example, the spring constant of thesecond tilting body 36 relative to force acting in the Z-axis directionmay be lower than the spring constant of the first tilting body 35relative to force acting in the Z-axis direction. FIG. 11 is a frontview illustrating a modification of the strain body in FIG. 4 .

According to a first modification illustrated in FIG. 11 , when force inthe Z-axis direction acts on the tilting structure 31, elasticdeformation of the first tilting body 35 can be inhibited, and elasticdeformation of the second tilting body 36 can be increased. Thus, thesecond tilting body 36 is greatly pulled up at both the ends 36 a and 36b thereof in the X-axis direction, and displacement of each of thedisplacement electrode substrates Ed1 and Ed2 provided on the secondtilting body 36 can be increased. Thus, detection sensitivity of forceor moment can be enhanced more.

Although the dimension of the first tilting body 35 in the Z-axisdirection is increased in order to increase the above-described springconstant of the first tilting body 35 in the example illustrated in FIG.11 , the spring constant of the first tilting body 35 is increased byany means. The above-described spring constant of the second tiltingbody 36 may be decreased. It should be noted that the spring constant ofthe second tilting body 36 relative to force acting in the Z-axisdirection may be higher than the spring constant of the first tiltingbody 35 relative to force acting in the Z-axis direction. In this case,the fixed electrode substrates Ef1 and Ef2 may be provided on thesurface of the force receiving body 10 on the side of the support body20, and the displacement electrode substrates Ed1 and Ed2 may beprovided on the surface of the first tilting body 35 of the tiltingstructure 31 on the side of the force receiving body 10.

(Second Modification)

It should be noted that in the example described above in the presentembodiment, the entire surface of the first tilting body 35 of the firststrain body 30A on the side of the force receiving body 10 is formedinto a flat shape, and the entire surface of the second tilting body 36on the side of the support body 20 is formed into a flat shape. However,the present embodiment is not limited thereto. For example, asillustrated in FIG. 12 , the surface of the first tilting body 35 on theside of the force receiving body 10 may be formed into a recessed shapearound the force-receiving-body-side deformable body 33. Moreover, thesurface of the second tilting body 36 on the side of the support body 20may be formed into a recessed shape around the support-body-sidedeformable body 34. FIG. 12 is a plan view illustrating anothermodification of the strain body in FIG. 4 .

More specifically, as illustrated in FIG. 12 , the first tilting body 35may include a first force-receiving-body-side facing surface 41 and asecond force-receiving-body-side facing surface 42 that face the forcereceiving body 10. The force-receiving-body-side deformable body 33 isconnected to the first force-receiving-body-side facing surface 41. Thesecond force-receiving-body-side facing surface 42 is disposed on bothsides of the first force-receiving-body-side facing surface 41 in theX-axis direction. The first force-receiving-body-side facing surface 41is located on the side of the support body 20 with respect to the secondforce-receiving-body-side facing surface 42. The firstforce-receiving-body-side facing surface 41 is formed around theforce-receiving-body-side deformable body 33. The firstforce-receiving-body-side facing surface 41 is farther from the forcereceiving body 10 than the second force-receiving-body-side facingsurface 42. In this way, the surface of the first tilting body 35 on theside of the force receiving body 10 is formed into a recessed shape, andthe force-receiving-body-side deformable body 33 is connected to theportion that is formed into a recessed shape. The firstforce-receiving-body-side facing surface 41 is formed over the centralportion 35 c of the first tilting body 35 and a portion in its vicinity,and a groove G is formed around the force-receiving-body-side deformablebody 33 (corresponding to both sides in the X-axis direction in theexample illustrated in FIG. 12 ). Each of the firstforce-receiving-body-side facing surface 41 and the secondforce-receiving-body-side facing surface 42 may be formed into a flatshape. It should be noted that in the example illustrated in FIG. 12 ,the force-receiving-body-side deformable body 33 and the first tiltingbody 35 of the tilting structure 31 are integrally formed into acontinuous shape, and the first force-receiving-body-side facing surface41 is illustrated on both sides of the force-receiving-body-sidedeformable body 33.

Thus, according to a second modification, the first tilting body 35includes the first force-receiving-body-side facing surface 41 locatedon the side of the support body 20 with respect to the secondforce-receiving-body-side facing surface 42, and theforce-receiving-body-side deformable body 33 is connected to the firstforce-receiving-body-side facing surface 41. Accordingly, the dimensionof the force-receiving-body-side deformable body 33 in the Z-axisdirection can be made longer. Thus, the force sensor 1 can be reduced inheight and made compact without reducing the dimension of theforce-receiving-body-side deformable body 33 in the Z-axis direction.

It should be noted that although not illustrated, the entire surface ofthe second tilting body 36 on the side of the support body 20 may beformed into a flat shape when the first tilting body 35 includes thefirst force-receiving-body-side facing surface 41 located on the side ofthe support body 20 with respect to the second force-receiving-body-sidefacing surface 42.

Similarly, the second tilting body 36 may include a firstsupport-body-side facing surface 43 and a second support-body-sidefacing surface 44 that face the support body 20. The support-body-sidedeformable body 34 is connected to the first support-body-side facingsurface 43. The second support-body-side facing surface 44 is disposedon both sides of the first support-body-side facing surface 43 in theX-axis direction. The first support-body-side facing surface 43 islocated on the side of the force receiving body 10 with respect to thesecond support-body-side facing surface 44. The first support-body-sidefacing surface 43 is formed around the support-body-side deformable body34. The first support-body-side facing surface 43 is farther from thesupport body 20 than the second support-body-side facing surface 44. Inthis way, the surface of the second tilting body 36 on the side of thesupport body 20 is formed into a recessed shape, and thesupport-body-side deformable body 34 is connected to the portion that isformed into a recessed shape. The first support-body-side facing surface43 is formed over the central portion 36 c of the second tilting body 36and a portion in its vicinity, and a groove G is formed around thesupport-body-side deformable body 34 (corresponding to both sides in theX-axis direction in the example illustrated in FIG. 12 ). Each of thefirst support-body-side facing surface 43 and the secondsupport-body-side facing surface 44 may be formed into a flat shape. Itshould be noted that in the example illustrated in FIG. 12 , thesupport-body-side deformable body 34 and the second tilting body 36 ofthe tilting structure 31 are integrally formed into a continuous shape,and the first support-body-side facing surface 43 is illustrated on bothsides of the support-body-side deformable body 34.

Thus, according to the second modification, the second tilting body 36includes the first support-body-side facing surface 43 located on theside of the force receiving body 10 with respect to the secondsupport-body-side facing surface 44, and the support-body-sidedeformable body 34 is connected to the first support-body-side facingsurface 43. Accordingly, the dimension of the support-body-sidedeformable body 34 in the Z-axis direction can be made longer. Thus, theforce sensor 1 can be reduced in height and made compact withoutshortening the dimension of the support-body-side deformable body 34 inthe Z-axis direction.

It should be noted that when the second tilting body 36 includes thefirst support-body-side facing surface 43 located on the side of theforce receiving body 10 with respect to the second support-body-sidefacing surface 44, the entire surface of the first tilting body 35 onthe side of the force receiving body 10 may be formed into a flat shapeas illustrated in FIG. 13 . In the example illustrated in FIG. 13 , thefirst tilting body 35 does not include the firstforce-receiving-body-side facing surface 41 described above, and thegroove G is not formed around the force-receiving-body-side deformablebody 33. The groove G is formed around the support-body-side deformablebody 34 on the surface of the second tilting body 36 on the side of thesupport body 20. FIG. 13 is a plan view illustrating anothermodification of the strain body in FIG. 4 .

(Third Modification)

In the example described above in the present embodiment, thedisplacement electrode substrates Ed1 and Ed2 of the first strain body30A are provided on the surface of the second tilting body 36 of thetilting structure 31 on the side of support body 20. However, thepresent embodiment is not limited thereto. For example, as illustratedin FIG. 14 , the displacement electrode substrates Ed1 and Ed2 may beprovided on the surface of the second tilting body 36 on the side of thesupport body 20 via a columnar member 45. FIG. 14 is a partiallyenlarged front view illustrating another modification of the strain bodyin FIG. 4 .

In the example illustrated in FIG. 14 , the planar shape of the columnarmember 45 may be smaller than the planar shape of each of thedisplacement electrode substrates Ed1 and Ed2. The planar shape of thecolumnar member 45 may be rectangular or circular, and may be any shape.The columnar member 45 may be joined to the second tilting body 36 byadhesive, or may be fixed thereto by a bolt or the like. Thedisplacement electrode substrates Ed1 and Ed2 may be joined to thecolumnar member 45 by adhesive, or may be fixed thereto by a bolt or thelike.

Thus, according to the third modification, the displacement electrodesubstrates Ed1 and Ed2 are provided to the second tilting body 36 viathe columnar member 45. Accordingly, detection of displacement can bestabilized. Specifically, when force acts on the first strain body 30A,the second tilting body 36 of the tilting structure 31 can beelastically deformed, and stress can be generated in the portions of thesecond tilting body 36 in the vicinity of the displacement electrodesubstrates Ed1 and Ed2. Generation of such stress causes the drift ofhysteresis or zero-point voltage (corresponding to output voltage whenno load is applied). On the contrary, as illustrated in FIG. 14 , theinfluence of stress generated in the second tilting body 36 on thedisplacement electrode substrates Ed1 and Ed2 can be reduced byproviding the displacement electrode substrates Ed1 and Ed2 to thesecond tilting body 36 via the columnar member 45. Thus, detection ofdisplacement can be stabilized.

(Fourth Modification)

As illustrated in FIG. 15 , the displacement electrode substrates Ed1and Ed2 may be provided on the columnar member 45 described above via areinforcing substrate 46. FIG. 15 is a partially enlarged front viewillustrating another modification of the strain body in FIG. 4 .

In the example illustrated in FIG. 15 , the planar shape of thereinforcing substrate 46 may be equal to the planar shape of each of thedisplacement electrode substrates Ed1 and Ed2. The reinforcing substrate46 may be joined to the columnar member 45 by adhesive, or may be fixedthereto by a bolt or the like. In this case, the displacement electrodesubstrates Ed1 and Ed2 may be joined to the reinforcing substrate 46 byadhesive. The spring constant of the reinforcing substrate 46 relativeto force acting in the Z-axis direction may be higher than the springconstant of the displacement electrode substrates Ed1 and Ed2 relativeto force acting in the Z-axis direction. Accordingly, deformation of thedisplacement electrode substrates Ed1 and Ed2 can be inhibited. Thereinforcing substrate 46 may be configured by a metal material, and maybe of the same material as the force receiving body 10, the support body20, and the strain bodies 30A to 30D in order to inhibit deformation dueto temperature changes, for example. In this case, the reinforcingsubstrate 46 may be configured by an aluminum alloy or an iron alloy.The reinforcing substrate 46 may be manufactured integrally with thecolumnar member 45 described above. Deformation of the displacementelectrode substrates Ed1 and Ed2 can be inhibited by using such areinforcing substrate 46. For example, even when FPC substrates are usedfor the displacement electrode substrates Ed1 and Ed2, deformation ofthe displacement electrode substrates Ed1 and Ed2 can be effectivelyinhibited.

(Fifth Modification)

In the example described above in the present embodiment, the firsttilting body 35 and the second tilting body 36 linearly extend in theX-axis direction (corresponding to the second direction of the firststrain body 30A). However, without being limited thereto, the firsttilting body 35 and the second tilting body 36 can have any shape aslong as the first tilting body 35 and the second tilting body 36 aredisposed in a plane including the Z-axis direction (corresponding tofirst direction) and the X-axis direction, and extend in a directiondifferent from the Z-axis direction. For example, the first tilting body35 and the second tilting body 36 may have a shape illustrated in FIG.16 . Here, FIG. 16 is a front view illustrating another modification ofthe strain body in FIG. 4 . It should be noted that the first strainbody 30A illustrated in FIG. 16 has a shape similar to that of the firststrain body 30A when receiving the force Fz on the negative side in theZ-axis direction as illustrated in FIG. 7B, but is illustrated as thefirst strain body 30A when receiving no action of force or moment inFIG. 16 .

In the first strain body 30A illustrated in FIG. 16 , the centralportion 35 c of the first tilting body 35 in the X-axis direction islocated on the side of the support body 20 (or on the side of the secondtilting body 36) with respect to both the ends 35 a and 35 b in theX-axis direction. More specifically, the first tilting body 35 includesa first-tilting-body negative-side portion 35 d disposed on the negativeside in the X-axis direction with respect to the central portion 35 c,and a first-tilting-body positive-side portion 35 e disposed on thepositive side in the X-axis direction with respect to the centralportion 35 c. The first-tilting-body negative-side portion 35 d is aportion connecting the negative-side end 35 a and the central portion 35c, and is inclined in such a way as to extend toward the negative sidein the Z-axis direction while extending toward to the positive side inthe X-axis direction. The first-tilting-body negative-side portion 35 dextends in a direction inclined relative to the Z-axis direction(corresponding to a direction different from the Z-axis direction) inthe XZ plane. The first-tilting-body positive-side portion 35 e is aportion connecting the positive-side end 35 b and the central portion 35c, and is inclined in such a way as to extend toward the positive sidein the Z-axis direction while extending toward the positive side in theX-axis direction. The first-tilting-body positive-side portion 35 eextends in a direction inclined relative to the Z-axis direction(corresponding to a direction different from the Z-axis direction) inthe XZ plane. In this way, the first tilting body 35 in the modificationillustrated in FIG. 16 is schematically formed into a V-shape.

The central portion 36 c of the second tilting body 36 in the X-axisdirection is located on the side of the force receiving body 10 (or onthe side of the first tilting body 35) with respect to both the ends 36a and 36 b in the X-axis direction. More specifically, the secondtilting body 36 includes a second-tilting-body negative-side portion 36d disposed on the negative side in the X-axis direction with respect tothe central portion 36 c, and a second-tilting-body positive-sideportion 36 e disposed on the positive side in the X-axis direction withrespect to the central portion 36 c. The second-tilting-bodynegative-side portion 36 d is a portion connecting the negative-side end36 a and the central portion 36 c, and is inclined in such a way as toextend toward the positive side in the Z-axis direction while extendingtoward the positive side in the X-axis direction. Thesecond-tilting-body negative-side portion 36 d extends in a directioninclined relative to the Z-axis direction (corresponding to a directiondifferent from the Z-axis direction) in the XZ plane. Thesecond-tilting-body positive-side portion 36 e is a portion connectingthe positive-side end 36 b and the central portion 36 c, and is inclinedin such a way as to extend toward the negative side in the Z-axisdirection while extending toward the positive side in the X-axisdirection. The second-tilting-body positive-side portion 36 e extends ina direction inclined relative to the Z-axis direction (corresponding toa direction different from the Z-axis direction) in the XZ plane. Inthis way, the second tilting body 36 in the modification illustrated inFIG. 16 is schematically formed into an inverted V-shape.

Thus, according to the modification illustrated in FIG. 16 , the centralportion 35 c of the first tilting body 35 in the X-axis direction islocated on the side of the support body 20 with respect to both the ends35 a and 35 b in the X-axis direction. Accordingly, the central portion35 c of the first tilting body 35 in the X-axis direction can be keptfar from the force receiving body 10, and the dimension of theforce-receiving-body-side deformable body 33 in the Z-axis direction canbe made longer. Thus, the force sensor 1 can be reduced in height andmade compact without reducing the dimension of theforce-receiving-body-side deformable body 33 in the Z-axis direction.

Moreover, according to the modification illustrated in FIG. 16 , thecentral portion 36 c of the second tilting body 36 in the X-axisdirection is located on the side of the force receiving body 10 withrespect to both the ends 36 a and 36 b in the X-axis direction.Accordingly, the central portion 36 c of the second tilting body 36 inthe X-axis direction can be kept far from the support body 20, and thedimension of the support-body-side deformable body 34 in the Z-axisdirection can be made longer. Thus, the force sensor 1 can be reduced inheight and made compact without reducing the dimension of thesupport-body-side deformable body 34 in the Z-axis direction.

(Sixth Modification)

In the example described above in the present embodiment, the firsttilting body 35 and the second tilting body 36 linearly extend in theX-axis direction (corresponding to the second direction of the firststrain body 30A). However, without being limited thereto, the firsttilting body 35 and the second tilting body 36 can have any shape aslong as the first tilting body 35 and the second tilting body 36 aredisposed in a plane including the Z-axis direction (corresponding tofirst direction) and the X-axis direction, and extend in a directiondifferent from the Z-axis direction. For example, the first tilting body35 and the second tilting body 36 may have a shape illustrated in FIG.17 . Here, FIG. 17 is a front view illustrating another modification ofthe strain body in FIG. 4 . It should be noted that the first strainbody 30A illustrated in FIG. 17 shows a shape similar to that of thefirst strain body 30A when receiving the force Fz on the positive sidein the Z-axis direction as illustrated in FIG. 7A, but is illustrated asthe first strain body 30A when receiving no action of force or moment inFIG. 17 .

In the first strain body 30A illustrated in FIG. 17 , the centralportion 35 c of the first tilting body 35 in the X-axis direction islocated on the side of the force receiving body 10 (or on the sideopposite to the second tilting body 36) with respect to both the ends 35a and 35 b in the X-axis direction. More specifically, theabove-described first-tilting-body negative-side portion 35 d of thefirst tilting body 35 is inclined in such a way as to extend toward thepositive side in the Z-axis direction while extending toward thepositive side in the X-axis direction. The first-tilting-bodypositive-side portion 35 e is inclined in such a way as to extend towardthe negative side in the Z-axis direction while extending toward thepositive side in the X-axis direction. In this way, the first tiltingbody 35 in the modification illustrated in FIG. 17 is schematicallyformed into an inverted V-shape.

The central portion 36 c of the second tilting body 36 in the X-axisdirection is located on the side of the support body 20 (or on the sideopposite to the first tilting body 35) with respect to both the ends 36a and 36 b in the X-axis direction. More specifically, theabove-described second-tilting-body negative-side portion 36 d of thesecond tilting body 36 is inclined in such a way as to extend toward thenegative side in the Z-axis direction while extending toward thepositive side in the X-axis direction. The second-tilting-bodypositive-side portion 36 e is inclined in such a way as to extend towardthe positive side in the Z-axis direction while extending toward thepositive side in the X-axis direction. In this way, the second tiltingbody 36 in the modification illustrated in FIG. 17 is schematicallyformed into a V-shape.

Thus, according to the modification illustrated in FIG. 17 , the centralportion 35 c of the first tilting body 35 in the X-axis direction islocated on the side of the force receiving body 10 with respect to boththe ends 35 a and 35 b in the X-axis direction. Accordingly, the forcesensor 1 can be increased in height without increasing the dimension ofthe force-receiving-body-side deformable body 33 in the Z-axisdirection.

Moreover, according to the modification illustrated in FIG. 17 , thecentral portion 36 c of the second tilting body 36 in the X-axisdirection is located on the side of the support body 20 with respect toboth the ends 36 a and 36 b in the X-axis direction. Accordingly, theforce sensor 1 can be increased in height without increasing thedimension of the support-body-side deformable body 34 in the Z-axisdirection.

(Seventh Modification)

In the example described above in the present embodiment, the upper endof the force-receiving-body-side deformable body 33 is connected to theforce receiving body 10. However, without being limited thereto, theforce-receiving-body-side deformable body 33 may be connected to theforce receiving body 10 via a force-receiving-body-side seat 39, forexample, as illustrated in FIG. 18 . Accordingly, theforce-receiving-body-side deformable body 33 can be stably attached tothe force receiving body 10 by the force-receiving-body-side seat 39.For example, the force-receiving-body-side seat 39, theforce-receiving-body-side deformable body 33, and the first tilting body35 may be integrally formed. In this case, the force-receiving-body-sideseat 39 may be fixed to the force receiving body 10 by a bolt, adhesive,or the like. Alternatively, the force-receiving-body-side seat 39 andthe force-receiving-body-side deformable body 33 may be separatelyformed and fixed to each other by a bolt, adhesive, or the like.

Similarly, without being limited to the configuration of having thelower end connected to the support body 20, the support-body-sidedeformable body 34 may be connected to the support body 20 via asupport-body-side seat 40, for example, as illustrated in FIG. 18 .Accordingly, the support-body-side deformable body 34 can be stablyattached to the support body 20 by the support-body-side seat 40. Forexample, the support-body-side seat 40, the support-body-side deformablebody 34, and the second tilting body 36 may be integrally formed. Inthis case, the support-body-side seat 40 may be fixed to the supportbody 20 by a bolt, adhesive, or the like. Alternatively, thesupport-body-side seat 40 and the support-body-side deformable body 34may be separately formed and fixed to each other by a bolt, adhesive, orthe like.

Furthermore, the force-receiving-body-side seat 39, theforce-receiving-body-side deformable body 33, the tilting structure 31,the support-body-side deformable body 34, and the support-body-side seat40 may be integrally formed. In this case, the force-receiving-body-sideseat 39 may be fixed to the force receiving body 10 by a bolt, adhesive,or the like, and the support-body-side seat 40 may be fixed to thesupport body 20 by a bolt, adhesive, or the like.

It should be noted that the force-receiving-body-side seat 39 and thesupport-body-side seat 40 are not exclusively applied to the firststrain body 30A illustrated in FIG. 18 , and can also be applied to theother strain bodies 30A to 30D including the first strain body 30Aillustrated in FIG. 11 .

(Eighth Modification)

In the example described above in the present embodiment, the planarshape of the force receiving body 10 is circular, and the tiltingstructure 31 is linearly formed along the second direction when viewedin the Z-axis direction. However, the present embodiment is not limitedthereto.

For example, as illustrated in FIG. 19 , the tilting structure 31 may beformed into a curved shape when viewed in the Z-axis direction. FIG. 19is a plan view illustrating another modification of the force sensor inFIG. 3 . In this case, the tilting structure 31 may be formed into acurved shape concentrically with the force receiving body 10.Specifically, the tilting structures 31 of the four strain bodies 30A to30D may be disposed in such a way as to form a circular annular shape.It should be noted that when the tilting structure 31 of each of thestrain bodies 30A to 30D is formed into a curved shape, the planar shapeof the force receiving body 10 may be rectangular as illustrated in FIG.20 described later. In this case, the planar shape of the support body20 may be rectangular.

For example, as illustrated in FIG. 20 , the planar shape of the forcereceiving body 10 may be rectangular. In this case, the planar shape ofthe support body 20 may also be rectangular. Accordingly, the forcereceiving body 10 and the support body 20 can be formed along thedisposition of the strain bodies 30A to 30D, and the force sensor 1having satisfactory space efficiency can be obtained. The planarsectional shape of the exterior body 80 may be a rectangular shape.Specifically, at least one of the planar shape of the force receivingbody 10 and the planar shape of the support body 20 may be rectangular.In this case, one of the planar shape of the force receiving body 10 andthe planar shape of the support body 20 may be rectangular, and theother may be a shape other than a rectangular shape. It should be notedthat the planar shape of the force receiving body 10 may be a shapeother than a rectangular shape, such as a polygonal or elliptical shape.The same also applies to the support body 20. In compliance with theplanar shapes of the force receiving body 10 and the support body 20,the planar sectional shape of the exterior body 80 may also be any othershape, such as a polygonal frame or an elliptical frame.

(Ninth Modification)

In the example described above in the present embodiment, the detectionelement 50 is configured as an element that detects capacitance.However, without being limited thereto, the detection element 50 may beconstituted by a strain gauge that detects strain produced by the actionof force or moment received by the force receiving body 10. For example,as illustrated in FIG. 21A, the detection element 50 may have a straingauge provided on the first strain body 30A. FIG. 21A is a front view ofa strain body illustrating a modification of the detection element inFIG. 4 . FIG. 21B is a plan view illustrating the detection element inFIG. 21A. FIG. 21C is a plan view illustrating a modification of FIG.21B. FIG. 22A is a view illustrating a Wheatstone bridge circuit for adetection element provided on a first tilting body illustrated in FIG.21A. FIG. 22B is a view illustrating a Wheatstone bridge circuit for adetection element provided on a second tilting body illustrated in FIG.21A. FIG. 23A is a schematic view illustrating a deformation state ofthe strain body in FIG. 21A when receiving force on the positive side inthe X-axis direction. FIG. 238 is a schematic view illustrating adeformation state of the strain body in FIG. 21A when receiving force onthe positive side in the Z-axis direction.

As illustrated in FIG. 21A, the strain gauges R1 to R8 may be providedon the tilting structure 31. It should be noted that as illustrated inFIGS. 23A and 23B, the dimension of each of the connecting bodies 37 and38 of the tilting structure 31 in the X-axis direction according to thepresent embodiment may be larger than the dimension of each of theconnecting bodies 37 and 38 of the tilting structure 31 in the X-axisdirection in FIG. 4 . In other words, the spring constant of each of theconnecting bodies 37 and 38 according to the present embodiment relativeto force acting in the X-axis direction may be higher than the springconstant of each of the connecting bodies 37 and 38 in FIG. 4 relativeto force acting in the X-axis direction.

More specifically, the strain gauges R1 to R4 may be attached to thesurface of the first tilting body 35 of the tilting structure 31 on theside of the force receiving body 10. For example, the two strain gaugesR1 and R2 may be attached to the upper surface of the first-tilting-bodynegative-side portion 35 d of the first tilting body 35, and the twostrain gauges R3 and R4 may be attached to the upper surface of thefirst-tilting-body positive-side portion 35 e. In the first-tilting-bodynegative-side portion 35 d, one strain gauge R1 may be located on theside of the end 35 a that is located on the negative side in the X-axisdirection (or on the side of the connecting body 37), and the otherstrain gauge R2 may be located on the side of the central portion 35 c(or on the side of the force-receiving-body-side deformable body 33). Inthe first-tilting-body positive-side portion 35 e, one strain gauge R3may be located on the side of the central portion 35 c (or on the sideof the force-receiving-body-side deformable body 33), and the otherstrain gauge R4 may be located on the side of the end 35 b that islocated on the positive side in the X-axis direction (or on the side ofthe connecting body 38). As illustrated in FIG. 21B, the four straingauges R1 to R4 provided on the first tilting body 35 may be located inthe center of the first tilting body 35 in the Y-axis direction.

As illustrated in FIG. 22A, the detection circuit 60 may have aWheatstone bridge circuit 61 that outputs an electric signal on thebasis of detection results by the four strain gauges R1 to R4 attachedto the first tilting body 35. This Wheatstone bridge circuit 61 isconfigured so that bridge voltage as an electric signal relevant tostrain detected by each of the strain gauges R1 to R4 is generatedbetween output terminals T11 and T12 by applying predetermined voltagefrom a bridge voltage source E1. In the Wheatstone bridge circuit 61,the strain gauge R1 and the strain gauge R3 face each other, and thestrain gauge R2 and the strain gauge R4 face each other. Accordingly,the force Fx in the X-axis direction can be detected as will bedescribed later, and the influence of the force Fz in the Z-axisdirection on the detection of the force Fx can be prevented.Specifically, the force Fx as main-axis sensitivity can be detected, andoccurrence of cross-axis sensitivity can be prevented.

As Illustrated in FIG. 21A, the strain gauges R5 to R8 may be attachedto the surface of the second tilting body 36 of the tilting structure 31on the side of the support body 20. For example, the two strain gaugesR5 and R6 may be attached to the lower surface of thesecond-tilting-body negative-side portion 36 d of the second tiltingbody 36, and the two strain gauges R7 and R8 may be attached to thelower surface of the second-tilting-body positive-side portion 36 e. Inthe second-tilting-body negative-side portion 36 d, one strain gauge R5may be located on the side of the end 36 a that is located on thenegative side in the X-axis direction (or on the side of the connectingbody 37), and the other strain gauge R6 may be located on the side ofthe central portion 36 c (or on the side of the support-body-sidedeformable body 34). In the second-tilting-body positive-side portion 36e, one strain gauge R7 may be located on the side of the central portion36 c (or on the side of the support-body-side deformable body 34), andthe other strain gauge R8 may be located on the side of the end 36 bthat is located on the positive side in the X-axis direction (or on theside of the connecting body 38). The strain gauges R5 to R8 provided onthe second tilting body 36 may be disposed in a manner similar to thestrain gauges R1 to R4 provided on the first tilting body 35 illustratedin FIG. 21B.

As illustrated in FIG. 22B, the detection circuit 60 may further have aWheatstone bridge circuit 62 that outputs an electric signal on thebasis of detection results by the four strain gauges R5 to R8 attachedto the second tilting body 36. This Wheatstone bridge circuit 62 isconfigured so that bridge voltage as an electric signal relevant tostrain detected by each of the strain gauges R5 to R8 is generatedbetween output terminals T21 and T22 by applying predetermined voltagefrom a bridge voltage source E2. In the Wheatstone bridge circuit 62,the strain gauge R5 and the strain gauge R8 face each other, and thestrain gauge R6 and the strain gauge R7 face each other. Accordingly,the force Fz in the Z-axis direction can be detected as will bedescribed later, and the influence of the force Fx in the X-axisdirection on the detection of the force Fz can be prevented.Specifically, the force Fz as main-axis sensitivity can be detected, andoccurrence of cross-axis sensitivity can be prevented.

It should be noted that the strain gauges R5 to R8 provided on thesecond tilting body 36 may be provided on the first tilting body 35.Specifically, the eight strain gauges R1 to R8 may be provided on thefirst tilting body 35. In this case, as illustrated in FIG. 21C, twocolumns of strain gauges along the X-axis direction may be formed on thesurface of the first tilting body 35 on the side of the force receivingbody 10. Accordingly, attachment of the eight strain gauges R1 to R8does not need to be performed on the surface of the second tilting body36 on the side of the support body 20, and can thus be performed only onthe surface of the first tilting body 35 on the side of the forcereceiving body 10, so that manufacturing work can be more efficient.Alternatively, the eight strain gauges R1 to R8 may be provided on thesurface of the second tilting body 36 on the side of the support body20. In this case, attachment of the eight strain gauges R1 to R8 doesnot need to be performed on the surface of the first tilting body 35 onthe side of the force receiving body 10, and can thus be performed onlyon the surface of the second tilting body 36 on the side of the supportbody 20, so that manufacturing work can be more efficient.

Due to such a configuration, when the force receiving body 10 receivesthe action of force or moment, the tilting structure 31 and thesupport-body-side deformable body 34 are elastically deformed primarily,and the first tilting body 35 and the second tilting body 36 of thetilting structure 31 are also elastically deformed. When the firsttilting body 35 is elastically deformed, strain is produced in the firsttilting body 35, and this strain is detected by the strain gauges R1 toR4 provided on the first tilting body 35.

For example, when the force Fx acts on the positive side in the X-axisdirection, the force-receiving-body-side deformable body 33 and thesupport-body-side deformable body 34 of the tilting structure 31 areinclined relative to the Z-axis direction, and the entire tiltingstructure 31 can tilt, as illustrated in FIG. 6 . To describe in moredetail, the first tilting body 35 and the second tilting body 36 areelastically deformed in such a way as to curve, as illustrated in FIG.23A. Compressive stress is produced in a part of the first-tilting-bodynegative-side portion 35 d on the side of the end 35 a that is locatedon the negative side in the X-axis direction, and the resistance valuedecreases in response to compressive strain in the strain gauge R1located in this part. Tensile stress is produced in a part of thefirst-tilting-body negative-side portion 35 d on the side of the centralportion 35 c, and the resistance value increases in response to tensilestrain in the strain gauge R2 located in this part. Compressive stressis produced in a part of the first-tilting-body positive-side portion 35e on the side of the central portion 35 c, and the resistance valuedecreases in response to compressive strain in the strain gauge R3located in this part. Tensile stress is produced in a part of thefirst-tilting-body positive-side portion 35 e on the side of the end 35b that is located on the positive side in the X-axis direction, and theresistance value increases in response to tensile strain in the straingauge R4 located in this part.

In this way, the resistance values change in the strain gauges R1 to R4,and an electric signal indicating the force Fx in the X-axis directionacting on the first strain body 30A is output from each of outputterminals T11 and T12 of the Wheatstone bridge circuit 61 illustrated inFIG. 22A.

In each of the strain gauges R5 to R8 provided on the second tiltingbody 36, stress in a direction opposite to that in each of the straingauges R1 to R4 provided on the first tilting body 35 is produced, andthe resistance values change. However, no electric signal is output fromthe output terminals T21 and T22 of the Wheatstone bridge circuit 62illustrated in FIG. 22B.

For example, when the force Fz acts on the positive side in the Z-axisdirection, the first tilting body 35 and the second tilting body 36 ofthe tilting structure 31 are elastically deformed, as illustrated inFIG. 7A. To describe in more detail, the first tilting body 35 and thesecond tilting body 36 are elastically deformed in such a way as tocurve, as illustrated in FIG. 23B. Compressive stress is produced in apart of the second-tilting-body negative-side portion 36 d on the sideof the end 36 a that is located on the negative side in the X-axisdirection, and the resistance value decreases in response to compressivestrain in the strain gauge R5 located in this part. Tensile stress isproduced in a part of the second-tilting-body negative-side portion 36 don the side of the central portion 36 c, and the resistance valueincreases in response to tensile strain in the strain gauge R6 locatedin this part. Tensile stress is produced in a part of thesecond-tilting-body positive-side portion 36 e on the side of thecentral portion 36 c, and the resistance value increases in response totensile strain in the strain gauge R7 located in this part. Compressivestress is produced in a part of the second-tilting-body positive-sideportion 36 e on the side of the end 36 b that is located on the positiveside in the X-axis direction, and the resistance value decreases inresponse to compressive strain in the strain gauge R8 located in thispart.

In this way, the resistance values change in the strain gauges R5 to R8,and an electric signal indicating the force Fz in the Z-axis directionacting on the first strain body 30A is output from each of outputterminals T21 and T22 of the Wheatstone bridge circuit 62 illustrated inFIG. 22B.

In each of the strain gauges R1 to R4 provided on the first tilting body35, stress in the same direction as that in the strain gauges R5 to R8provided on the second tilting body 36, and the resistance value thuschanges. However, no electric signal is output from the output terminalsT11 and T12 of the Wheatstone bridge circuit 61 illustrated in FIG. 22A.

By using the strain gauges R1 to R8 provided on the first strain body30A illustrated in FIG. 21A, the force Fx in the X-axis direction andthe force Fz in the Z-axis direction can be detected, and two axiscomponents of force can be detected. For example, by providing a straingauge in each of the strain bodies 30A to 30D illustrated in FIG. 5 ,the forces Fx, Fy, and Fz and the moments Mx, My, and Mz can bedetected, and six axis components of force can be detected.

In the example described in FIG. 21A, FIG. 23A, and FIG. 23B, the straingauges R1 to R4 are attached to the surface of the first tilting body 35on the side of the force receiving body 10. However, without beinglimited thereto, the strain gauges R1 to R4 may be attached to thesurface of the first tilting body 35 on the side of the support body 20(or the surface on the side of the second tilting body 36), as indicatedby broken lines in FIGS. 23A and 23B. In this case, although therelation between compression and tension in the strain gauges R1 to R4is converse, the force Fz in the Z-axis direction can be detected in asimilar manner. The example in which the strain gauges R5 to R8 areattached to the surface of the second tilting body 36 on the side of thesupport body 20 is also described above. However, without being limitedthereto, the strain gauges R5 to R8 may be attached to the surface ofthe second tilting body 36 on the side of the force receiving body 10(or the surface on the side of the first tilting body 35), as indicatedby broken lines in FIGS. 23A and 23B. In this case, although therelation between compression and tension in the strain gauges R5 to R8is converse, the force Fx in the X-axis direction can be detected in asimilar manner.

In the example described in FIGS. 21A to 23B, the four strain gauges R1to R4 attached to the first tilting body 35 constitute the Wheatstonebridge circuit 61 illustrated in FIG. 22A, and thereby detect the forceFx in the X-axis direction. However, without being limited thereto, thefour strain gauges R1 to R4 may detect the force Fz in the Z-axisdirection. In this case, for example, in the Wheatstone bridge circuit61 illustrated in FIG. 22A, the strain gauge R3 and the strain gauge R4may be interchanged with each other. Similarly, in the example describedin FIGS. 21A to 23B, the four strain gauges R5 to R8 attached to thesecond tilting body 36 constitute the Wheatstone bridge circuit 62illustrated in FIG. 22B, and thereby detect the force Fz in the Z-axisdirection. However, without being limited thereto, the four straingauges R5 to R8 may detect the force Fx in the X-axis direction. In thiscase, for example, in the Wheatstone bridge circuit 62 illustrated inFIG. 22B, the strain gauge R7 and the strain gauge R8 may beinterchanged with each other.

Second Embodiment

Next, a force sensor in a second embodiment of the present invention isdescribed by use of FIGS. 24 to 28 .

The second embodiment illustrated in FIGS. 24 to 28 is different fromthe first embodiment illustrated in FIGS. 1 to 238 mainly in that aforce receiving body and a first tilting body are connected by twoforce-receiving-body-side deformable bodies, and a support-body-sidedeformable body connects the first tilting body and a support body. Inother respects, the configuration according to the second embodiment issubstantially the same as that according to the first embodiment. Itshould be noted that the same reference signs are given in FIGS. 24 to28 to the same parts as those in the first embodiment illustrated inFIGS. 1 to 23B, and thus detailed description is omitted.

First, a force sensor 1 according to the present embodiment is describedwith reference to FIG. 24 . FIG. 24 is a front view illustrating astrain body of the force sensor in the second embodiment.

In the force sensor 1 according to the present embodiment, asillustrated in FIG. 24 , a tilting structure 31 of a first strain body30A is configured by one first tilting body 35. The tilting structure 31according to the present embodiment does not include a second tiltingbody 36 and connecting bodies 37 and 38 illustrated in FIG. 4 . In thepresent embodiment, the first tilting body 35 extends in an X-axisdirection. More specifically, the first tilting body 35 linearly extendsin the X-axis direction from one end 35 a of the first tilting body 35to the other end 35 b, and a central portion 35 c of the first tiltingbody 35 in the X-axis direction is located at the same position in theZ-axis direction as both the ends 35 a and 35 b. The entire surface ofthe first tilting body 35 on the side of a force receiving body 10 isformed into a flat shape. Moreover, the entire surface of the firsttilting body 35 on the side of a support body 20 is formed into a flatshape.

The force receiving body 10 and the first tilting body 35 are connectedby two force-receiving-body-side deformable bodies 33 extending in theZ-axis direction. The two force-receiving-body-side deformable bodies 33are disposed at positions different from each other in the X-axisdirection. In the example illustrated in FIG. 24 , the twoforce-receiving-body-side deformable bodies 33 are located at both theends 35 a and 35 b of the first tilting body 35 in the X-axis direction.In the present embodiment, each of the force-receiving-body-sidedeformable bodies 33 has an upper end connected to the force receivingbody 10 and a lower end connected to the first tilting body 35.

A support-body-side deformable body 34 is located between the twoforce-receiving-body-side deformable bodies 33 in the X-axis direction.More specifically, the support-body-side deformable body 34 is locatedin the center of the first tilting body 35 in the X-axis direction, andis connected to the central portion 35 c of the first tilting body 35.In the present embodiment, the support-body-side deformable body 34 hasa lower end connected to the support body 20 and an upper end connectedto the first tilting body 35.

In this way, the first strain body 30A is formed symmetrically withrespect to the support-body-side deformable body 34 in the X-axisdirection.

Next, a method of detecting force or moment acting on the force sensor 1in the present embodiment having such a configuration as above isdescribed with reference to FIGS. 25 to 26B. FIG. 25 is a front viewschematically illustrating a deformation state of the strain body inFIG. 24 when receiving force on the positive side in the X-axisdirection. FIG. 26A is a front view schematically illustrating adeformation state of the strain body in FIG. 24 when receiving force onthe positive side in the Z-axis direction. FIG. 26B is a front viewschematically illustrating a deformation state of the strain body inFIG. 24 when receiving force on the negative side in the Z-axisdirection.

Here, the first strain body 30A is taken for example to describe changesin capacitance value of a first capacitative element C1 and a secondcapacitative element C2 on which force Fx in the X-axis direction, forceFy in the Y-axis direction, and force Fz in the Z-axis direction act.

(When +Fx Acts)

When the force Fx acts on the first strain body 30A on the positive sidein the X-axis direction, the two force-receiving-body-side deformablebodies 33 and the support-body-side deformable body 34 of the firststrain body 30A are elastically deformed in the X-axis direction asillustrated in FIG. 25 . Since the first tilting body 35 of the tiltingstructure 31 according to the present embodiment is connected to theforce receiving body 10 via the two force-receiving-body-side deformablebodies 33 and is also connected to the support body 20 via onesupport-body-side deformable body 34, the support-body-side deformablebody 34 can be elastically deformed more than theforce-receiving-body-side deformable bodies 33. More specifically, theupper end of the support-body-side deformable body 34 is relativelygreatly displaced to the positive side in the X-axis direction more thanthe lower end. Accordingly, as illustrated in FIG. 25 , the twoforce-receiving-body-side deformable bodies 33 and the first tiltingbody 35 can be tilted together with the force receiving body 10 as awhole. In this instance, although not illustrated in FIG. 25 , each ofthe force-receiving-body-side deformable bodies 33 is also elasticallydeformed, and the upper end of each of the force-receiving-body-sidedeformable bodies 33 can be displaced to the positive side in the X-axisdirection more than the lower end. Thus, the support-body-sidedeformable body 34 of the first strain body 30A can be elasticallydeformable mainly by the force Fx on the positive side in the X-axisdirection. In this case, the end 35 a of the first tilting body 35 onthe negative side in the X-axis direction rises, and the end 35 b on thepositive side in the X-axis direction lowers.

Accordingly, a first displacement electrode substrate Ed1 moves awayfrom a first fixed electrode substrate Ef1, and the capacitance value ofthe first capacitative element C1 decreases. Moreover, a seconddisplacement electrode substrate Ed2 moves closer to a second fixedelectrode substrate Ef2, and the capacitance value of the secondcapacitative element C2 increases.

(When −Fx Acts)

Although not illustrated, a phenomenon opposite to the case illustratedin FIG. 25 occurs when the force Fx acts on the first strain body 30A onthe negative side in the X-axis direction. Specifically, the capacitancevalue of the first capacitative element C1 increases, and thecapacitance value of the second capacitative element C2 decreases.

(When +Fy Acts)

When the force Fy acts on the first strain body 30A on the positive sidein the Y-axis direction (not illustrated), the first strain body 30Aturns around the X-axis (corresponding to counterclockwise toward thepositive side in the X-axis direction). As described above, the firstcapacitative element C1 and the second capacitative element C2 aredisposed at the same position in the Y-axis direction. Thus, even whenthe first strain body 30A turns around the X-axis, the capacitance valueincreases in some regions of the first capacitative element C1, and thecapacitance value decreases in other regions. Therefore, no change incapacitance value appears in the whole first capacitative element C1.Similarly, no change in capacitance value appears in the whole secondcapacitative element C2.

(When −Fy Acts)

When the force Fy acts on the first strain body 30A on the negative sidein the Y-axis direction as well, no changes in capacitance value appearin the whole first capacitative element C1 and the whole secondcapacitative element C2.

(When +Fz Acts)

When the force Fz acts on the first strain body 30A on the positive sidein the Z-axis direction, the first tilting body 35 of the tiltingstructure 31 is elastically deformed as illustrated in FIG. 26A. Morespecifically, while the first tilting body 35 is elastically deformed,the two force-receiving-body-side deformable bodies 33 are pulled up tothe positive side in the Z-axis direction. Accordingly, the firsttilting body 35 is pulled up by the force-receiving-body-side deformablebodies 33 at both the ends 35 a and 35 b in the X-axis direction asillustrated in FIG. 26A. On the other hand, the central portion 35 c ofthe first tilting body 35 in the X-axis direction is connected to thesupport-body-side deformable body 34, and is therefore substantially notpulled up. Thus, the first tilting body 35 is elastically deformed insuch a way as to project downward (e.g., a V-shape).

As Illustrated in FIG. 26A, when the first tilting body 35 iselastically deformed, the first displacement electrode substrate Ed1moves away from the first fixed electrode substrate Ef1. Thus, thecapacitance value of the first capacitative element C1 decreases.Moreover, the second displacement electrode substrate Ed2 moves awayfrom the second fixed electrode substrate Ef2. Thus, the capacitancevalue of the second capacitative element C2 decreases.

(When −Fz Acts)

When the force Fz acts on the first strain body 30A on the negative sidein the Z-axis direction, the first tilting body 35 of the tiltingstructure 31 is elastically deformed as illustrated in FIG. 26B. Morespecifically, while the first tilting body 35 is elastically deformed,the force-receiving-body-side deformable bodies 33 are pulled down tothe negative side in the Z-axis direction. Accordingly, the firsttilting body 35 is pulled down by the force-receiving-body-sidedeformable bodies 33 at both the ends 35 a and 35 b of the first tiltingbody 35 in the X-axis direction as illustrated in FIG. 26B. On the otherhand, the central portion 35 c of the first tilting body 35 in theX-axis direction is connected to the support-body-side deformable body34, and is therefore substantially not pulled down. Thus, the firsttilting body 35 is elastically deformed in such a way as to projectupward (e.g., an inverted V-shape).

As illustrated in FIG. 26B, when the first tilting body 35 iselastically deformed, the first displacement electrode substrate Ed1moves closer to the first fixed electrode substrate Ef1. Thus, thecapacitance value of the first capacitative element C1 increases.Moreover, the second displacement electrode substrate Ed2 moves closerto the second fixed electrode substrate Ef2. Thus, the capacitance valueof the second capacitative element C2 increases.

Thus, according to the present embodiment, the force receiving body 10and the first tilting body 35 are connected by the twoforce-receiving-body-side deformable bodies 33, and thesupport-body-side deformable body 34 connects the first tilting body 35and the support body 20. Accordingly, the dimension of the tiltingstructure 31 in the Z-axis direction can be reduced. Thus, the forcesensor 1 can be reduced in height and made compact.

According to the present embodiment, the two force-receiving-body-sidedeformable bodies 33 of the first strain body 30A are located betweenboth the ends 35 a and 35 b of the first tilting body 35 in the X-axisdirection. Accordingly, the first tilting body 35 can be elasticallydeformed more easily by the action of force in the Z-axis direction.Thus, displacement of each of the displacement electrode substrates Ed1to Ed8 can be increased more easily, and detection sensitivity of forceor moment can be enhanced.

According to the present embodiment, the support-body-side deformablebody 34 of the first strain body 30A is located between the twoforce-receiving-body-side deformable bodies 33 in the X-axis direction.Accordingly, the first tilting body 35 can be elastically deformed moreeasily by the action of force in the Z-axis direction. Thus,displacement of each of the displacement electrode substrates Ed1 to Ed8can be increased more easily, and detection sensitivity of force ormoment can be enhanced.

According to the present embodiment, the strain bodies 30A to 30D areformed symmetrically with respect to the support-body-side deformablebody 34 in a second direction. Accordingly, when force in the Z-axisdirection acts, displacement of the first displacement electrodesubstrate Ed1 can be equalized to displacement of the seconddisplacement electrode substrate Ed2. Therefore, calculation of force ormoment can be eased.

(Tenth Modification)

In the example described above in the present embodiment, the entiresurface of the first tilting body 35 of the first strain body 30A on theside of the support body 20 is formed into a flat shape. However, thepresent embodiment is not limited thereto. For example, as illustratedin FIG. 27 , the surface of the first tilting body 35 on the side of thesupport body 20 may be formed into a recessed shape around thesupport-body-side deformable body 34. FIG. 27 is a plan viewillustrating a modification of the strain body in FIG. 24 .

More specifically, the first tilting body 35 may include a firstsupport-body-side facing surface 47 and a second support-body-sidefacing surface 48 that face the support body 20. The support-body-sidedeformable body 34 is connected to the first support-body-side facingsurface 47. The second support-body-side facing surface 48 is disposedon both sides of the first support-body-side facing surface 47 in theX-axis direction. The first support-body-side facing surface 47 islocated on the side of the force receiving body 10 with respect to thesecond support-body-side facing surface 48. The first support-body-sidefacing surface 47 is formed around the support-body-side deformable body34. The first support-body-side facing surface 47 is farther from thesupport body 20 than the second support-body-side facing surface 48. Inthis way, the surface of the first tilting body 35 on the side of thesupport body 20 is formed into a recessed shape, and thesupport-body-side deformable body 34 is connected to the portion that isformed into a recessed shape. The first support-body-side facing surface47 is formed over the central portion 35 c of the first tilting body 35and a portion in its vicinity, and a groove G is formed around thesupport-body-side deformable body 34 (corresponding to both sides in theX-axis direction in the example illustrated in FIG. 27 ). Each of thefirst support-body-side facing surface 47 and the secondsupport-body-side facing surface 48 may be formed into a flat shape. Itshould be noted that in the example illustrated in FIG. 27 , thesupport-body-side deformable body 34 and the first tilting body 35 ofthe tilting structure 31 are integrally formed into a continuous shape,and the first support-body-side facing surface 47 is illustrated on bothsides of the support-body-side deformable body 34.

Thus, according to the tenth modification, the first tilting body 35includes the first support-body-side facing surface 47 located on theside of the force receiving body 10 with respect to the secondsupport-body-side facing surface 48, and the support-body-sidedeformable body 34 is connected to the first support-body-side facingsurface 47. Accordingly, the dimension of the support-body-sidedeformable body 34 in the Z-axis direction can be made longer. Thus, theforce sensor 1 can be reduced in height and made compact withoutshortening the dimension of the support-body-side deformable body 34 inthe Z-axis direction.

(Eleventh Modification)

In the example described above in the present embodiment, the firsttilting body 35 linearly extends in the X-axis direction (correspondingto a second direction of the first strain body 30A). However, withoutbeing limited thereto, the first tilting body 35 and the second tiltingbody 36 can have any shape as long as the first tilting body 35 and thesecond tilting body 36 are disposed in a plane including the Z-axisdirection (corresponding to a first direction) and the X-axis directionand extend in a direction different from the Z-axis direction. Forexample, the first tilting body 35 and the second tilting body 36 mayhave a shape illustrated in FIG. 28 . Here, FIG. 28 is a front viewillustrating another modification of the strain body in FIG. 24 . Itshould be noted that the first strain body 30A illustrated in FIG. 28shows a shape similar to that of the strain body when receiving theforce Fz on the negative side in the Z-axis direction as illustrated inFIG. 26B, but is illustrated as the first strain body 30A when receivingno action of force or moment in FIG. 28 .

In the first strain body 30A illustrated in FIG. 28 , the centralportion 35 c of the first tilting body 35 in the X-axis direction islocated on the side of the force receiving body 10 with respect to boththe ends 35 a and 35 b in the X-axis direction. More specifically, thefirst tilting body 35 includes a first-tilting-body negative-sideportion 35 d disposed on the negative side in the X-axis direction and afirst-tilting-body positive-side portion 35 e disposed on the positiveside in the X-axis direction. The first-tilting-body negative-sideportion 35 d is a portion connecting the negative-side end 35 a and thecentral portion 35 c, and is inclined in such a way as to extend towardthe positive side in the Z-axis direction while extending toward thepositive side in the X-axis direction. The first-tilting-bodynegative-side portion 35 d extends in a direction (corresponding to adirection different from the Z-axis direction) inclined relative to theZ-axis direction in an XZ plane. The first-tilting-body positive-sideportion 35 e is a portion connecting the positive-side end 35 b and thecentral portion 35 c, and is inclined in such a way as to extend towardthe negative side in the Z-axis direction while extending toward thepositive side in the X-axis direction. The first-tilting-bodypositive-side portion 35 e extends in a direction (corresponding to adirection different from the Z-axis direction) inclined relative to theZ-axis direction in the XZ plane. In this way, the first tilting body 35in the modification illustrated in FIG. 28 is schematically formed intoan inverted V-shape.

Thus, according to the modification illustrated in FIG. 28 , both theends 35 a and 35 b of the first tilting body 35 in the X-axis directionare located on the side of the support body 20 with respect to thecentral portion 35 c in the X-axis direction. Accordingly, both the ends35 a and 35 b of the first tilting body 35 in the X-axis direction canbe kept far from the force receiving body 10, and the dimension of theforce-receiving-body-side deformable body 33 in the Z-axis direction canbe made longer. Thus, the force sensor 1 can be reduced in height andmade compact without reducing the dimension of theforce-receiving-body-side deformable bodies 33 in the Z-axis direction.

According to the modification illustrated in FIG. 28 , the centralportion 35 c of the first tilting body 35 in the X-axis direction islocated on the side of the force receiving body 10 with respect to boththe ends 35 a and 35 b in the X-axis direction. Accordingly, the centralportion 35 c of the first tilting body 35 in the X-axis direction can bekept far from the support body 20, and the dimension of thesupport-body-side deformable body 34 in the Z-axis direction can be madelonger. Thus, the force sensor 1 can be reduced in height and madecompact without reducing the dimension of the support-body-sidedeformable body 34 in the Z-axis direction.

It should be noted that the form of the first tilting body 35 is notlimited to the example illustrated in FIG. 28 . For example, althoughnot illustrated, the central portion 35 c of the first tilting body 35in the X-axis direction may be located on the side of the support body20 with respect to both the ends 35 a and 35 b in the X-axis direction.In this case, the first tilting body 35 is schematically formed into aV-shape. Accordingly, the force sensor 1 can be increased in heightwithout increasing the dimension of the force-receiving-body-sidedeformable body 33 in the Z-axis direction and the dimension of thesupport-body-side deformable body 34 in the Z-axis direction.

(Twelfth Modification)

In the example described above in the present embodiment, theforce-receiving-body-side deformable body 33 extends in the Z-axisdirection. However, the present embodiment is not limited thereto. Forexample, as illustrated in FIGS. 29 and 30 , theforce-receiving-body-side deformable body 33 may be inclined relative tothe Z-axis direction when viewed in the Y-axis direction. FIG. 29 is aplan view illustrating another modification of the strain body in FIG.24 . FIG. 30 is a plan view illustrating another modification of thestrain body in FIG. 24 .

In the modification illustrated in FIG. 29 , the twoforce-receiving-body-side deformable bodies 33 are inclined relative tothe Z-axis direction in such a way as to be kept far from each othertoward the force receiving body 10. More specifically, theforce-receiving-body-side deformable body 33 located on the negativeside in the X-axis direction is inclined relative to the Z-axisdirection in such a way that the upper end is located on the negativeside in the X-axis direction with respect to the lower end. On the otherhand, the force-receiving-body-side deformable body 33 located on thepositive side in the X-axis direction is inclined relative to the Z-axisdirection in such a way that the upper end is located on the positiveside in the X-axis direction with respect to the lower end. In this way,the force receiving body 10, the two force-receiving-body-sidedeformable bodies 33, and the first tilting body 35 are disposed in theshape of an inverted trapezoid when viewed in the Y-axis direction.

Thus, according to the modification illustrated in FIG. 29 , the forcesensor 1 can be reduced in height and made compact without reducing thelongitudinal dimension of the force-receiving-body-side deformablebodies 33.

In the modification illustrated in FIG. 30 , the twoforce-receiving-body-side deformable bodies 33 are inclined relative tothe Z-axis direction in such a way as to be kept close to each othertoward the force receiving body 10. More specifically, theforce-receiving-body-side deformable body 33 located on the negativeside in the X-axis direction is inclined relative to the Z-axisdirection in such a way that the upper end is located on the positiveside in the X-axis direction with respect to the lower end. On the otherhand, the force-receiving-body-side deformable body 33 located on thepositive side in the X-axis direction is inclined relative to the Z-axisdirection in such a way that the upper end is located on the negativeside in the X-axis direction with respect to the lower end. In this way,the force receiving body 10, the two force-receiving-body-sidedeformable bodies 33, and the first tilting body 35 are disposed in theshape of a trapezoid when viewed in the Y-axis direction.

Thus, according to the modification illustrated in FIG. 30 , the forcesensor 1 can be reduced in height and made compact without reducing thelongitudinal dimension of the force-receiving-body-side deformable body33.

(Thirteenth Modification)

In the example described above in the present embodiment, the upper endof each of the force-receiving-body-side deformable bodies 33 isconnected to the force receiving body 10. However, without being limitedthereto, each of the force-receiving-body-side deformable bodies 33 maybe connected to the force receiving body 10 via aforce-receiving-body-side seat 39, for example, as illustrated in FIG.31 . Accordingly, each of the force-receiving-body-side deformablebodies 33 can be stably attached to the force receiving body 10 by theforce-receiving-body-side seat 39. For example, theforce-receiving-body-side seat 39, the force-receiving-body-sidedeformable body 33, and the first tilting body 35 may be integrallyformed. In this case, each of the force-receiving-body-side seats 39 maybe fixed to the force receiving body 10 by a bolt, adhesive, or thelike. Alternatively, the force-receiving-body-side seat 39 and theforce-receiving-body-side deformable body 33 may be separately formedand fixed to each other by a bolt, adhesive, or the like.

Similarly, without being limited to the configuration of having thelower end connected to the support body 20, the support-body-sidedeformable body 34 may be connected to the support body 20 via asupport-body-side seat 40, for example, as illustrated in FIG. 31 .Accordingly, the support-body-side deformable body 34 can be stablyattached to the support body 20 by the support-body-side seat 40. Forexample, the support-body-side seat 40, the support-body-side deformablebody 34, and the first tilting body 35 may be integrally formed. In thiscase, the support-body-side seat 40 may be fixed to the support body 20by a bolt, adhesive, or the like. Alternatively, the support-body-sideseat 40 and the support-body-side deformable body 34 may be separatelyformed and fixed to each other by a bolt, adhesive, or the like.

Furthermore, the force-receiving-body-side seat 39, theforce-receiving-body-side deformable body 33, the tilting structure 31,the support-body-side deformable body 34, and the support-body-side seat40 may be integrally formed. In this case, the force-receiving-body-sideseat 39 may be fixed to the force receiving body 10 by a bolt, adhesive,or the like, and the support-body-side seat 40 may be fixed to thesupport body 20 by a bolt, adhesive, or the like.

It should be noted that the force-receiving-body-side seat and thesupport-body-side seat are not exclusively applied to the first strainbody 30A illustrated in FIG. 31 , and can also be applied to the otherstrain bodies 30A to 30D including the first strain body 30A illustratedin FIG. 24 and the like.

(Fourteenth Modification)

In the example described above in the present embodiment, the detectionelement 50 is configured as an element that detects capacitance.However, without being limited thereto, the detection element 50 may beconstituted by a strain gauge (see FIGS. 21A to 23B) that detects strainproduced by the action of force or moment received by the forcereceiving body 10. For example, the strain gauges R1 to R4 may beattached to the surface of the first tilting body 35 of the tiltingstructure 31 on the side of the force receiving body 10, and the straingauges R5 to R8 may be attached to the surface of the first tilting body35 on the side of the support body 20. In this case, the strain gaugesR1 to R4 and the strain gauges R5 to R8 may be disposed as illustratedin FIG. 21B. Moreover, for example, the strain gauges R1 to R8 may beattached to the surface of the first tilting body 35 on the side of theforce receiving body 10, or to the surface on the side of the supportbody 20, as illustrated in FIG. 21C.

The present invention is not completely limited to the embodiments andmodifications described above, and can be embodied by modifying thecomponents without departing from the spirit thereof at the stage ofimplementation. Moreover, various inventions can be formed by a suitablecombination of a plurality of components disclosed in the embodimentsand modifications described above. Some components may be deleted fromall of the components disclosed in the embodiments and modificationsdescribed above. Further, the components in different embodiments andmodifications may be suitably combined.

The invention claimed is:
 1. A force sensor comprising: a forcereceiving body that receives action of force or moment to be targetedfor detection; a support body that is disposed on one side of the forcereceiving body in a first direction and that supports the forcereceiving body; a strain body that connects the force receiving body andthe support body and that is elastically deformed by the action of forceor moment received by the force receiving body; a detection element thatdetects displacement caused by elastic deformation produced in thestrain body; and a detection circuit that outputs an electric signalindicating force or moment acting on the strain body, on the basis of adetection result by the detection element, wherein the strain bodyincludes a tilting structure disposed between the force receiving bodyand the support body, a force-receiving-body-side deformable body thatconnects the force receiving body and the tilting structure, theforce-receiving-body-side deformable body being elastically deformableby the action of force or moment received by the force receiving body,and a support-body-side deformable body that connects the tiltingstructure and the support body, the support-body-side deformable bodybeing elastically deformable by the action of force or moment receivedby the force receiving body, and the tilting structure includes a firsttilting body that is disposed in a plane including the first directionand a second direction orthogonal to the first direction, the firsttilting body extending in a direction different from the first directionand being elastically deformable by the action of force in the firstdirection, the tilting structure further includes a second tilting bodythat is disposed between the first tilting body and the support body,the second tilting body being disposed in a plane including the firstdirection and the second direction, extending in a direction differentfrom the first direction, and being elastically deformable by the actionof force in the first direction, and a pair of connecting bodiesconnecting one of the both ends of the first tilting body in the seconddirection and a corresponding one of the both ends of the second tiltingbody in the second direction, the force-receiving-body-side deformablebody is connected to the first tilting body, the support-body-sidedeformable body is connected to the second tilting body.
 2. The forcesensor according to claim 1, wherein the force-receiving-body-sidedeformable body extends in the first direction.
 3. The force sensoraccording to claim 1, wherein the support-body-side deformable bodyextends in the first direction.
 4. The force sensor according to claim1, wherein the force-receiving-body-side deformable body is locatedbetween both the ends of the first tilting body in the second direction.5. The force sensor according to claim 1, wherein the support-body-sidedeformable body is located between both the ends of the second tiltingbody in the second direction.
 6. The force sensor according to claim 1,wherein the second tilting body extends in the second direction, thesecond tilting body includes a first support-body-side facing surface towhich the support-body-side deformable body is connected, the firstsupport-body-side facing surface facing the support body, and a secondsupport-body-side facing surface that is disposed on both sides of thefirst support-body-side facing surface in the second direction, thesecond support-body-side facing surface facing the support body, and thefirst support-body-side facing surface is located on the side of theforce receiving body with respect to the second support-body-side facingsurface.
 7. The force sensor according to claim 1, wherein theforce-receiving-body-side deformable body is connected to the forcereceiving body via a force-receiving-body-side seat, and thesupport-body-side deformable body is connected to the support body via asupport-body-side seat.
 8. The force sensor according to claim 1,wherein the detection element includes a fixed electrode substrateprovided on the force receiving body or the support body and adisplacement electrode substrate provided on the tilting structure, thedisplacement electrode substrate facing the fixed electrode substrate,and the displacement electrode substrate is disposed at both ends of thetilting structure in the second direction.
 9. The force sensor accordingto claim 8, wherein the displacement electrode substrate is provided onthe tilting structure via a columnar member.
 10. The force sensoraccording to claim 9, wherein the displacement electrode substrate isprovided on the columnar member via a reinforcing substrate.
 11. Theforce sensor according to claim 1, wherein the detection dement includesa strain gauge provided on the strain body.
 12. The force sensoraccording to claim 1, wherein the force receiving body and the supportbody are connected by the four strain bodies, the four strain bodiesinclude a first strain body, a second strain body, a third strain body,and a fourth strain body, the first direction is a Z-axis direction inan XYZ three-dimensional coordinate system, the first strain body isdisposed on a negative side in the Y-axis direction relative to a centerof the force receiving body, the second strain body is disposed on apositive side in the X-axis direction relative to the center of theforce receiving body, the third strain body is disposed on a positiveside in the Y-axis direction relative to the center of the forcereceiving body, and the fourth strain body is disposed on a negativeside in the X-axis direction relative to the center of the forcereceiving body, the second direction of the first strain body and thethird strain body is the X-axis direction, and the second direction ofthe second strain body and the fourth strain body is the Y-axisdirection.
 13. The force sensor according to claim 12, wherein at leastone of the planar shape of the force receiving body and the planar shapeof the support body is circular or rectangular, and the tiltingstructure of the strain body is formed into a curved shape when viewedin the first direction.